Deck core on older boats

[Tranona]

Oh! Some examples showing the deck layer cut away reveal just a large area of balsa. The GRP 'ribs' I mentioned at 12" intervals seemed to be supporting between the two decks, The sandwiched blocks seemed to offer insulation rather than structural rigidity.

Some cored deck looks like that when you cut through if the core is un sections with with solid grp forming a grid. Does it have a smooth inner skin?

 

[pcatterall]

Some cored deck looks like that when you cut through if the core is un sections with with solid grp forming a grid. Does it have a smooth inner skin?

Yes, it is the smooth part of the mould, very smart still after 50 years!!

 

[Ceirwan]

As I understood the cored debate conclusions, it was as much or more about cost and temperature insulation incorporated into the deck itself, rather than weight. I think designed obsolescence was also a reason for lower quality cored builds; they didn't want or expect those boats to still be used 40 years later.

If it were solely about weight to strength ratio, with latest carbon-aramid hybrid laminates becoming rather affordable, solid laminate decks should be making a comeback.
Perhaps, they are, but I am not aware of that. As far as I read, a solid laminate boat, alternating carbon and aramid layers with glass, would be much lighter and stronger than even cored GRP boats are.
(I think latest Bluewater brand fork of Hylas is doing that to some extent.)

On the boat I mentioned, we are planning to restore all areas with penetrations by using solid laminate - not just drilled oversize and filled with epoxy.

Strength is a somewhat meaningless term without being specific, as there are many different properties of strength, in the case of a deck its more about stiffness to weight.
And sandwich construction is way ahead, If you built in carbon fibre, you could make it safe to walk on fairly easily, but to achieve the same stiffness you would need to have a very thick laminate.
If going the carbon route it would make more sense to make the carbon into a sandwich construction as well.

Well, it certainly SHOULD be.

The test of time has shown that what was quite obviously an awful idea at conception is in fact an awful idea in practice.

Unless, of course, one actually likes the idea of disposable boats...

Absolute nonsense. Boats from the 70s with cored decks are still going strong, despite being nearly 50 years old now, as long as they're maintained its not an issue. And they can be repaired as well.
Its like suggesting that boats made from wood are disposable because you need to paint and maintain them...

 

[ducked]

Its like suggesting that boats made from wood are disposable because you need to paint and maintain them...

I doubt, if you hadnt, that I would feel the need to "suggest" such a bleedin obvious fact, demonstrated by the number of wooden boats that have been disposed of because the need to paint and maintain them has not been met.

Historically, that would be almost all of them.

And a boat with a balsa core, is, in a very real sense, a wooden boat, but its designer has voluntarily chosen to install a wood with vey low durability in a difficult to access, and thus maintain, location.

Keel hauling would be appropriate, since deck hauling isn't a thing.

Many of the freebie boats posted on the relevent sites for "re-homing" (and still more that are being scrapped) are there because core repair is deemed (by experts, already) to be impractical.

This MIGHT represent an opportunity to the occaisional impecunious optimist, but that doesnt make it a Good Thing.

 

[Ceirwan]

I doubt, if you hadnt, that I would feel the need to "suggest" such a bleedin obvious fact, demonstrated by the number of wooden boats that have been disposed of because the need to paint and maintain them has not been met.

Historically, that would be almost all of them.

And a boat with a balsa core, is, in a very real sense, a wooden boat, but its designer has voluntarily chosen to install a wood with vey low durability in a difficult to access, and thus maintain, location.

Keel hauling would be appropriate, since deck hauling isn't a thing.

Many of the freebie boats posted on the relevent sites for "re-homing" (and still more that are being scrapped) are there because core repair is deemed (by experts, already) to be impractical.

This MIGHT represent an opportunity to the occaisional impecunious optimist, but that doesnt make it a Good Thing.

I really don't know what comment you're trying to make here.
No boat is a 'forever' item without extensive and ongoing maintenance, as you say historically almost all boats are no longer around.

Steel boats require painting and even so still degrade slowly and require replacement sections welding in over time.
Aluminium boats come close but need to be carefully protected from electrical corossion.
Wooden boats need paint and caulking.

And even GRP boats will degrade over time, GRP fatigues just like any other material and boats are flexing all the time they're at sea, even a solid 50s / 60s GRP hull will degrade over time and need remedial work.
Plus the gelcoat gets shot and needs painting or re-gelling, and on all the systems wear out, cabin furnishings degrade.

Have boats been abandoned because of a soggy deck core, certainly, but the issue isn't that it can't be repaired, just that its not economical to do so, in the same way that buying a new mast and all harken deck gear for a Newbridge Corribee isn't going to add 10K plus to value of the boat.
There are plenty of abandoned boats from the 60s with solid decks that nobody wants and are destined for landfill.

Everything in life is a trade off, a good foam is much better at water resistance in cored construction, but other than water intrusion, its very difficult to beat balsa as an all around core material.
A solid deck will be much heavier and much more flexible underfoot, unless it has extensive framing, disadvantages that mean that every GRP boat builder that I can think of uses sandwich construction.

And as I already said, a cored deck that is well maintained with all holes sealed correctly will last a long long time.
On my last boat it was still going strong even though it was 40 years old, if I buy something that is still in great condition after 40 years with basic maintenance, that's hardly what I'd describe as disposable.

 

[geem]

I really don't know what comment you're trying to make here.
No boat is a 'forever' item without extensive and ongoing maintenance, as you say historically almost all boats are no longer around.

Steel boats require painting and even so still degrade slowly and require replacement sections welding in over time.
Aluminium boats come close but need to be carefully protected from electrical corossion.
Wooden boats need paint and caulking.

And even GRP boats will degrade over time, GRP fatigues just like any other material and boats are flexing all the time they're at sea, even a solid 50s / 60s GRP hull will degrade over time and need remedial work.
Plus the gelcoat gets shot and needs painting or re-gelling, and on all the systems wear out, cabin furnishings degrade.

Have boats been abandoned because of a soggy deck core, certainly, but the issue isn't that it can't be repaired, just that its not economical to do so, in the same way that buying a new mast and all harken deck gear for a Newbridge Corribee isn't going to add 10K plus to value of the boat.
There are plenty of abandoned boats from the 60s with solid decks that nobody wants and are destined for landfill.

Everything in life is a trade off, a good foam is much better at water resistance in cored construction, but other than water intrusion, its very difficult to beat balsa as an all around core material.
A solid deck will be much heavier and much more flexible underfoot, unless it has extensive framing, disadvantages that mean that every GRP boat builder that I can think of uses sandwich construction.

And as I already said, a cored deck that is well maintained with all holes sealed correctly will last a long long time.
On my last boat it was still going strong even though it was 40 years old, if I buy something that is still in great condition after 40 years with basic maintenance, that's hardly what I'd describe as disposable.

My dinghy is 32 years old, in great shape and my daily ride. I can't see why it wouldn't be about in another 30 years. It's cored with foam with carbon reinforcement. My yacht is 45 years old. Airex foam core hull and deck. All in great condition. It also now has some carbon reinforcement to the skeg area just to make it more sexy

 

[ducked]

My dinghy is 32 years old, in great shape and my daily ride. I can't see why it wouldn't be about in another 30 years. It's cored with foam with carbon reinforcement. My yacht is 45 years old. Airex foam core hull and deck. All in great condition. It also now has some carbon reinforcement to the skeg area just to make it more sexy

Weeell MEIGH boat is 58 yurs old, was essentially abandoned for the last 4-5 years, and had young...er...make that yooong...brambles growing from t'mook ont'decks, which still seemed solid like a millstone.

No fancy pants ceirbon feiber in them days, nor no blooody leightweiyt balsa bollocks neither, lookilly

(Of course there MIGHT be something else seriously wrong with it that I dont know about yet, No point in tempting fate.

Based on a partial failure of part of the rubbing strake, I'm rather afraid some of the hidden fittings may be mild steel, almost as horrible and indefensible as balsa core if it turns out to be general. Not quite as horrible, but perhaps as indefensible.

Of course these fittings are enclosed, so I suppose you could argue that with adequate construction and maintenance they need never get wet and should last for ever, and that water resistance is thus an irrelevent characteristic for maritime structural materials, and boats.)

 

[Ceirwan]

Is it not enough for you to be satisfied with your own boat?

I've quite clearly laid out the reasons that basically every single yard / naval architect will specify a cored deck. If Balsa is a no no for you, then you can find plenty of boats with foam cored decks (geems being an example).
And mild steel parts are a false equivalence, there are clear advantages to sandwich construction, weight, stiffness, and insulation. The only reason to use a mild steel fitting is to save money.

If you're happy with what you have, great, no ones forcing you to switch.

 

[ducked]

Is it not enough for you to be satisfied with your own boat?

I've quite clearly laid out the reasons that basically every single yard / naval architect will specify a cored deck. If Balsa is a no no for you, then you can find plenty of boats with foam cored decks (geems being an example).
And mild steel parts are a false equivalence, there are clear advantages to sandwich construction, weight, stiffness, and insulation. The only reason to use a mild steel fitting is to save money.

If you're happy with what you have, great, no ones forcing you to switch.

My (provisional) personal satisfaction with my own boat doesnt require me to like every feature of anyone elses. To suggest otherwise seems to be a falser equivalence (or a falser contrast, I get confused).

To the limited extent that there's a corelation, its probably negative, my awareness of balsa sandwich constructions tendency to disintegrate compensating me for my lack of its clear advantages and increasing my appreciation of its abscence, a particularly valuable feature in the case of the old neglected boats that I can afford.

Similarly, my awareness of the non-maintainability of new cars probably enhanced my appreciation of my ancient car while I had it, but I still largely despise new cars despite whatever advantages are claimed for them.

IMO, which is mine, Balsa core flies in the face of the maritime practical and aesthetic tradition of durability to an offensive degree. Foam core isnt so bad.

The "no one's forcing you to switch" thing that always gets trotted out in such cases is just a space filler, and doesnt affect my opinion or its validity in any way.

No ones forcing you to switch either.

So what?

But, as it happens, if/when all the solid decked boats/old cars/etc become economically unavailable, then I would be, and in fact have been, forced to switch or do without.

 

[Ceirwan]

That's a bit of a jumbled word salad of a post you've made there.

But at the risk of repeating myself:

• Sandwich construction offer's considerable advantages over a solid laminate layup. In weight / stiffness / insulation & these days cost as well as resin is getting quite expensive.
• The weight saving is considerable and given that extra weight right on top of the boat is the last place you want it for stability & seaworthiness, its a double win.
• There are lots of different cores that can be used, Foam is great. But Balsa equally is a suitable material, provided care is taken to look after it.

Your boat is no doubt full of interior construction made from Plywood and other perishable materials, what happens if you have a deck leak that isn't fixed. They rot, the thousands of hours of youtube video of people pulling old soggy bulkheads out of their 60s 'they don't build em like that anymore' boats will attest to that.
To follow your line of thinking through, every bulkhead should be a solid piece of GRP laminate, every piece of framing, etc.
Clearly that's going to make for a very heavy, slow, and quite ugly down below boat.

The only way water gets into a balsa cored deck is if hardware has been installed incorrectly.
Modern builders take out the core in areas where deck hardware is bolted & make it either solid laminate or occasionally put in a stainless plate into the laminate.

And if as a boat owner you need to install something extra, its really simply, drill an oversize hole, fill with thickened epoxy. Drill the correct size hole. That's it.
Literally that one extra step will mean that even if your deck fittings start leaking, the core is protected and the deck will last as long as the boat.

If you want to throw out some scenario in which the owner has indiscriminately drilled holes & the boat has been left abandoned for years, covered in moss and slime, then yeah, in that very particular scenario, the solid deck will fare better than the balsa and when buying an abandoned project boat its definitely something that has to be considered and planned for, in the same way the rusting seized lump of cast iron under the companionway will probably need replacing.

I would hope that you maintain your boats, and if you do then you'd have nothing to worry about.

Similarly, my awareness of the non-maintainability of new cars probably enhanced my appreciation of my ancient car while I had it, but I still largely despise new cars despite whatever advantages are claimed for them.

Well given that cored decks are circa 70s, they are probably older than the old car that you drive around .

Modern cars are repairable, the diagnosis methods are a bit different, you need a good scan tool to help with diagnosis. But everything else is no different than the past. If you can change the McPherson struts on an old car, you can do it a new one, Brake pads on discs are far easier than brake shoes on drum brakes to change. Ball joints, bushes, non of this stuff has changed.
Engines might be more complicated on the face of it, but timing belts, water pumps and changing sensors are all easily achievable by a competent DIYer.

The only point I'd agree with is on the electrical systems, modern cars are starting to get very complicated on that front, mainly driven by every more integrated systems, but there is a lot of help available online these days which wasn't around years ago so it does help offset that.

 

[doug748]

Many of the freebie boats posted on the relevent sites for "re-homing" (and still more that are being scrapped) are there because core repair is deemed (by experts, already) to be impractical.

This MIGHT represent an opportunity to the occaisional impecunious optimist, but that doesnt make it a Good Thing.

Indeed, old boats don't need additional problems. We have enough to deal with without cored decks, bolt on iron keels or saildrive engines but there we are.
The quest for jumbo boats at cheap prices has blessed us with these compromises.


.

 

[ducked]

That's a bit of a jumbled word salad of a post you've made there.

But at the risk of repeating myself:

• Sandwich construction offer's considerable advantages over a solid laminate layup. In weight / stiffness / insulation & these days cost as well as resin is getting quite expensive.
• The weight saving is considerable and given that extra weight right on top of the boat is the last place you want it for stability & seaworthiness, its a double win.
• There are lots of different cores that can be used, Foam is great. But Balsa equally is a suitable material, provided care is taken to look after it.

Your boat is no doubt full of interior construction made from Plywood and other perishable materials, what happens if you have a deck leak that isn't fixed. They rot, the thousands of hours of youtube video of people pulling old soggy bulkheads out of their 60s 'they don't build em like that anymore' boats will attest to that.
To follow your line of thinking through, every bulkhead should be a solid piece of GRP laminate, every piece of framing, etc.
Clearly that's going to make for a very heavy, slow, and quite ugly down below boat.

I took your "Its like suggesting that boats made from wood are disposable because you need to paint and maintain them..." to imply that that would be a ridiculous thing to do, yet here you are attempting a similar number on marine ply bulkheads,

But perhaps that was just dressing on your word salad.

The important differences between marine ply bulkheads and balsa core, which make it a "false equivalence" include:-

1. They are made from the same durable woods and glues as are used for the hulls of wooden boats, either as timber or as plywood.
2. They are accessible, which allows inspection and drying out.
3. If degraded, due to that accessability, they are relatively easy to repair or replace, as shown in your own post

None of this applies to balsa sealed within a deck structure.

One of the most prominent "free boat" sites will not make boats with extensive deck core problems available for re-homing and simply scraps them without the option.

Presumably this gate keeping is because experience suggests repair is impractical and they dont want abandoned projects and unsafe repairs to damage their reputation.

I rather doubt this is entirely correct and would be very tempted to have a go, or at least I would have been when I was younger, but I'm not an expert, and have never attempted a core repair, so I'd be very much the sort of impecunious optimist they are probably wary of.

If I DID attempt core replacement, you can bet I would not be replacing it with more ****** balsa.

 

[geem]

I took your "Its like suggesting that boats made from wood are disposable because you need to paint and maintain them..." to imply that that would be a ridiculous thing to do, yet here you are attempting a similar number on marine ply bulkheads,

But perhaps that was just dressing on your word salad.

The important differences between marine ply bulkheads and balsa core, which make it a "false equivalence" include:-

1. They are made from the same durable woods and glues as are used for the hulls of wooden boats, either as timber or as plywood.
2. They are accessible, which allows inspection and drying out.
3. If degraded, due to that accessability, they are relatively easy to repair or replace, as shown in your own post

None of this applies to balsa sealed within a deck structure.

One of the most prominent "free boat" sites will not make boats with extensive deck core problems available for re-homing and simply scraps them without the option.

Presumably this gate keeping is because experience suggests repair is impractical and they dont want abandoned projects and unsafe repairs to damage their reputation.

I rather doubt this is entirely correct and would be very tempted to have a go, or at least I would have been when I was younger, but I'm not an expert, and have never attempted a core repair, so I'd be very much the sort of impecunious optimist they are probably wary of.

If I DID attempt core replacement, you can bet I would not be replacing it with more ****** balsa.

On two seperate boats I have had plywood failure where the ply was used in the core space as a reinforcement. The first was under the mast on a Prout Snowgoose 37. Water had gotten in from a previous mast base where the old bolts holes had been poorly sealed. I had to cut the grp off and scoop the rotten ply out with a spoon. It was like wet toilet paper.
The second was a very similar problem under my windlass. Again, the deck was cut out and the ply was scooped out. Rotten as pulp.
Ply substructure under teak decks on Taiwanese boats are a known failure point. There doesn't seem to be much difference to balsa in terms of the durability once it gets wet.
A Warrior 40 left in English Harbour boatyard in Antigua got termites in the balsa core deck. It is presumed from a bad repair, they somehow found their way in. Nobody is quite sure. The balsa deck was simply eaten away. The insurers wrote the boat off! 3 guys bought the boat cheap and cut the deck off. New core was installed and the old deck was refitted. Filled and faired and painted and they got themselves an excellent deal overall.
A failed core deck is not the end of the world if you are a Practical Boat Owner

 

[ducked]

On two seperate boats I have had plywood failure where the ply was used in the core space as a reinforcement. The first was under the mast on a Prout Snowgoose 37. Water had gotten in from a previous mast base where the old bolts holes had been poorly sealed. I had to cut the grp off and scoop the rotten ply out with a spoon. It was like wet toilet paper.
The second was a very similar problem under my windlass. Again, the deck was cut out and the ply was scooped out. Rotten as pulp.
Ply substructure under teak decks on Taiwanese boats are a known failure point. There doesn't seem to be much difference to balsa in terms of the durability once it gets wet.
A Warrior 40 left in English Harbour boatyard in Antigua got termites in the balsa core deck. It is presumed from a bad repair, they somehow found their way in. Nobody is quite sure. The balsa deck was simply eaten away. The insurers wrote the boat off! 3 guys bought the boat cheap and cut the deck off. New core was installed and the old deck was refitted. Filled and faired and painted and they got themselves an excellent deal overall.
A failed core deck is not the end of the world if you are a Practical Boat Owner

I'm unsure if you are suggesting I implied that a ply cored deck was a good thing, or just supplying information, but if the former that is incorrect.

I would expect plywood cored deck to be about the same, because the plywood is sealed in glassfibre, so it lacks points 2 and 3 above which, as I said, make a ply bulkhead superior/not really comparable to a deck. The greater durability of the timber might buy some time, but OTOH the biaxial orientation of the veneers will promote lateral movement of water. Might be a bit more resistant to termite attack though.

Nature finds a way again. I wonder if you could employ the little buggers to remove the balsa and then inject foam.

Are balsa cored bulkheads a thing? I suppose not, because they'll be potentially exposed to bilge water, arent walked on, and the weight saving on a bulkhead would be less useful

 

[Ceirwan]

I took your "Its like suggesting that boats made from wood are disposable because you need to paint and maintain them..." to imply that that would be a ridiculous thing to do, yet here you are attempting a similar number on marine ply bulkheads,

Actually I have no issues with plywood bulkhead, if maintained its a good material to make them from.

However you made it clear that you're happy to accept a significant weight and performance penalty in order to have a boat that's more tolerant of neglect, therefore I'm actually surprised that you would accept anything less than a GRP bulkhead in solid laminate, which would last far better than a plywood one.
You can even go one better, J boats for example have the main bulkhead made from a foam fore sandwich, greater stiffness & completely rot proof, while also avoiding the main downside of the plywood which is that polyester resin just doesn't stick that well to it.

The important differences between marine ply bulkheads and balsa core, which make it a "false equivalence" include:-

1. *snip*

None of this applies to balsa sealed within a deck structure.

But as I've pointed out multiple times in this thread, a balsa cored deck will last the life time of the boat with the extremely simple of rule of sealing the core off if you drill a hole in it. Probably less maintenance than a plywood bulkhead which needs paint or varnish refreshing.
I'll reiterate though, I have no issue with plywood as a material. Its good enough for the job.

One of the most prominent "free boat" sites will not make boats with extensive deck core problems available for re-homing and simply scraps them without the option.

And?
Your talking about a boat that has been left for so long that is has to be given away. Hardly something you should expect a designer to plan for.
And most of these old boats are going to be scrapped regardless of how the deck was built, as they are just not economical to refit.

Presumably this gate keeping is because experience suggests repair is impractical and they dont want abandoned projects and unsafe repairs to damage their reputation.

I rather doubt this is entirely correct and would be very tempted to have a go, or at least I would have been when I was younger, but I'm not an expert, and have never attempted a core repair, so I'd be very much the sort of impecunious optimist they are probably wary of.

A core repair is time consuming and involved but easily within the realm of a practical DIYer and like replacing a bulkhead there are many many videos on youtube showing how it should be done. (and probably just as many showing how it shouldn't.

If I DID attempt core replacement, you can bet I would not be replacing it with more ****** balsa.

People sometimes use Plywood which works but is very heavy.
Foam is ideal, but if a deck was not designed with it in mind it would be a lot more involved as a foam core will generally be thicker than a balsa core (different material properties) and probably have a different skin laminate.

I get that you don't like deck cores, but this seems to be more of an ideological point rather than a practical one at this point.
You're prepared to ignore the huge benefits of a sandwich deck construction, simply to have a boat that's a little more resistant to neglect.

Hallberg Rassy / Swan / Oyster / X-Yachts / Rustler, the most premium yacht builders I could think of from the top of my head, all specify sandwich decks. These people make some of the most well regarded designs in the world.

 

[ducked]

Actually I have no issues with plywood bulkhead, if maintained its a good material to make them from.

However you made it clear that you're happy to accept a significant weight and performance penalty in order to have a boat that's more tolerant of neglect, therefore I'm actually surprised that you would accept anything less than a GRP bulkhead in solid laminate, which would last far better than a plywood one.
You can even go one better, J boats for example have the main bulkhead made from a foam fore sandwich, greater stiffness & completely rot proof, while also avoiding the main downside of the plywood which is that polyester resin just doesn't stick that well to it.


But as I've pointed out multiple times in this thread, a balsa cored deck will last the life time of the boat with the extremely simple of rule of sealing the core off if you drill a hole in it. Probably less maintenance than a plywood bulkhead which needs paint or varnish refreshing.
I'll reiterate though, I have no issue with plywood as a material. Its good enough for the job.



And?
Your talking about a boat that has been left for so long that is has to be given away. Hardly something you should expect a designer to plan for.
And most of these old boats are going to be scrapped regardless of how the deck was built, as they are just not economical to refit.



A core repair is time consuming and involved but easily within the realm of a practical DIYer and like replacing a bulkhead there are many many videos on youtube showing how it should be done. (and probably just as many showing how it shouldn't.



People sometimes use Plywood which works but is very heavy.
Foam is ideal, but if a deck was not designed with it in mind it would be a lot more involved as a foam core will generally be thicker than a balsa core (different material properties) and probably have a different skin laminate.

I get that you don't like deck cores, but this seems to be more of an ideological point rather than a practical one at this point.
You're prepared to ignore the huge benefits of a sandwich deck construction, simply to have a boat that's a little more resistant to neglect.

Hallberg Rassy / Swan / Oyster / X-Yachts / Rustler, just the most premium yacht builder I could think of from the top of my head, all specify sandwich decks. These people make some of the most well regarded designs in the world.

I would accept, and have already said, that a lot of my objection to balsa core is aesthetic, not a synonym for ideological, but perhaps close enough. I find the idea of voluntarily sealing a non-durable material into a boat structure offensive, even if the most premium yacht builders you can think of can get away with it, perhaps for a very long time.

Its also, however, a very practical consideration for me, since I have a free boat, and might consider another one someday. Neglect can often be assumed in that context, and certainly applies to mine, but some are apparently well maintained and only have a survey featuring a rotten deck core putting them on the list.

Heres an example

Elizabethan 23

I have seen accounts of the leak path being built in to the construction, rather than caused by subsequent owners. I cant remember which builders were involved so cant give you examples, and dont know if they included some of the most well regarded yacht designs in the world, but it wouldnt astonish me if that were the case.

 

[geem]

I would accept, and have already said, that a lot of my objection to balsa core is aesthetic, not a synonym for ideological, but perhaps close enough. I find the idea of voluntarily sealing a non-durable material into a boat structure offensive, even if the most premium yacht builders you can think of can get away with it, perhaps for a very long time.

Its also, however, a very practical consideration for me, since I have a free boat, and might consider another one someday. Neglect can often be assumed in that context, and certainly applies to mine, but some are apparently well maintained and only have a survey featuring a rotten deck core putting them on the list.

Heres an example

Elizabethan 23

I have seen accounts of the leak path being built in to the construction, rather than caused by subsequent owners. I cant remember which builders were involved so cant give you examples, and dont know if they included some of the most well regarded yacht designs in the world, but it wouldnt astonish me if that were the case.

A 1969 designed boat?

 

[ducked]

A 1969 designed boat?

Uh? A 1969 designed boat...er...WHAT?

I assume you mean the Liz 23. Sailboatdata.com has it as first built in 1969.

I dunno when it was designed, but up above somewhere balsa core is said to be a 70's thing, so 1969 is almost there.

I thought this was about the same age as mine, but apparently the first one was built 1960 (which may explain the lack of core), so it could be up to 65 years old, and must be at least 51

Whats your point?

 

[Ceirwan]

Uh? A 1969 designed boat...er...WHAT?

I assume you mean the Liz 23. Sailboatdata.com has it as first built in 1969.

I dunno when it was designed, but up above somewhere balsa core is said to be a 70's thing, so 1969 is almost there.

I thought this was about the same age as mine, but apparently the first one was built 1960 (which may explain the lack of core), so it could be up to 65 years old, and must be at least 51

Whats your point?

I think just that its a 56 year old boat that's clearly been neglected.
Honestly if you can pull out rotten bulkheads and fix the other multitude of sins on a boat, a deck core repair is not that bad, especially on an older boat like that where preserving a gelcoat deck finish is normally not a concern, so you can work from the top.

Mark out the suspected damp areas, moisture meter, hammer, drill into the core, lots of ways to check.
Cut off the top skin, keep going until you find good core, or do sections at a time, depending how bad it is, use common sense.

Remove old core, if soggy and rotten its very easy to do.
Install sand inner skin, acetone wipe.
Bed new core balsa or otherwise on bed of either thickened epoxy (best) or a good marine polyester bonding paste (acceptable).

In many cases you can reuse the top skin, after suitable prep work. Again bed it down on thickened epoxy or polyester bonding paste.
Then grind a good taper in the edges of that laminate and tie it back together with glass fibre.
Makes sure you soak balsa or plywood with polyester or epoxy resin before bonding to each skin. (depending what paste you use)

Sand, fair. (minimal if using old skin)

Realistically on a boat that size, its a few weekends work.
And this is a project boat, you expect jobs to do. Had you owned this from new, and looked after it the deck would still be good now.
Modern boats would fare even better as designers now use solid laminate or other core materials in way of deck penetrations.

Anyway, I think this one has run its course, lets agree to to disagree, I think our types of sailing and boat are a long way apart.

 

[ducked]

I think just that its a 56 year old boat that's clearly been neglected.
Honestly if you can pull out rotten bulkheads and fix the other multitude of sins on a boat, a deck core repair is not that bad, especially on an older boat like that where preserving a gelcoat deck finish is normally not a concern, so you can work from the top.

Mark out the suspected damp areas, moisture meter, hammer, drill into the core, lots of ways to check.
Cut off the top skin, keep going until you find good core, or do sections at a time, depending how bad it is, use common sense.

Remove old core, if soggy and rotten its very easy to do.
Install sand inner skin, acetone wipe.
Bed new core balsa or otherwise on bed of either thickened epoxy (best) or a good marine polyester bonding paste (acceptable).

In many cases you can reuse the top skin, after suitable prep work. Again bed it down on thickened epoxy or polyester bonding paste.
Then grind a good taper in the edges of that laminate and tie it back together with glass fibre.
Makes sure you soak balsa or plywood with polyester or epoxy resin before bonding to each skin. (depending what paste you use)

Sand, fair. (minimal if using old skin)

Realistically on a boat that size, its a few weekends work.
And this is a project boat, you expect jobs to do. Had you owned this from new, and looked after it the deck would still be good now.
Modern boats would fare even better as designers now use solid laminate or other core materials in way of deck penetrations.

Anyway, I think this one has run its course, lets agree to to disagree, I think our types of sailing and boat are a long way apart.

Realistically, had I owned this boat from new, I would probably be dead.

That said, I would also think it should be fixable, (though at least some of "the experts" in the freeboat/scrapboat field seem to disagree), I would perhaps attempt it differently, and I dont see where your evidence is for neglect, unless its based on the mere fact of core degradation, which would be a bit of rather circular self justifying logic.

Perhaps my own boat as a reference standard for neglect induces a different perspective. but that one seems to have been looked after and had a fair bit of money (even a recent survey, already) spent on it.

You also give a hint of an acknowledgement there that, in executing this (deplorable, IMO, natch) innovation, sloppy building practices might have compounded the original sin. I suppose this boat is a fairly early example of cored construction, so the comittment to ignoring the bleedin obvious would perhaps be especially strong.

Anyway, I was asking Geem what his point was, and, while the above is of interest, you are not he.