Balsa Core Boats

I've had one, a Lightwave 395.
Never had any issues with core rotting, but these boats were better made than some, being vacuum bagged when built.
I did have some issues with the skin coming adrift from the core where collison or mooring damage had been poorly repaired.
You are at the mercy of previous owners IMHO.
 
Rival 41C. Balsa cored cabin roof. No issues at all. However, it is a heavy layup and probably doesn't need the balsa core that much.

However, you are correct to be worried, but sensible precautions and good fitting and mounting practices would eliminate the worry.
 
lw395 said:
I've had one, a Lightwave 395.
Never had any issues with core rotting, but these boats were better made than some, being vacuum bagged when built.
I did have some issues with the skin coming adrift from the core where collison or mooring damage had been poorly repaired.
You are at the mercy of previous owners IMHO.
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Agree entirely that the problem is what previous owners have done... Many years ago I had a small boat with sodden balsa coachroof top, which I did eventually fix, but a horrible job. No obvious sign until I drilled a small hole up into the inner skin to fix a light, and water poured out! On tracing the leak I found several badly bedded fittings topside.
 
jwilson said:
Agree entirely that the problem is what previous owners have done... Many years ago I had a small boat with sodden balsa coachroof top, which I did eventually fix, but a horrible job. No obvious sign until I drilled a small hole up into the inner skin to fix a light, and water poured out! On tracing the leak I found several badly bedded fittings topside.
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I'm having a guy drill holes to inspect exactly this as a requirement prior to purchase as there is a degree of delamination above normal on the coach roof of a boat I'm looking at.
 
I think most decks are cored these days, certainly more than hulls. Decks are more prone to having holes drilled in them for a plethora of fittings, while the hull only has a few holes in it.

A small amount of core failure in a coachroof does not threaten the boat in the way that core failure in the hull might though. It is a horrible job to repair though, if it spreads.
 
I have a Club 19 which has a balsa cored hull and dick but a solid transom, all fiittings need to be fitted correctly by drilling larger than required holes first, then removing some core followed by filling with epoxy then redrilling smaller holes to fit fittings.
This is something some owners cannot be bothered with so checking previous ownership and a good survey is a must.
 
I must admit that once I have chosen my next boat, first question would be to find out if the hull is Balsa Core. Until recently I had never heard of this method of construction, I certainly thought that hulls were GRP all the way through. I was talking to a Powerboat Instructor who mentioned this method of construction and he was wondering if when a boat hull flexes the outer thin GRP could come unglued from the balsa core and then start to wear with constant flexing.
Time will tell. (But not with my money)
 
I can assure you my 1984 boat has been raced and moored on a drying berth, all be it soft mud, the balsa cored hull is in great shape no signs of any delamination so I think the power boat instructors scare mongering are incorrect.
It actually makes for a lighter stronger hull, the balsa by the way is end on so very strong against any knocks.
 
Jim@sea said:
I must admit that once I have chosen my next boat, first question would be to find out if the hull is Balsa Core. Until recently I had never heard of this method of construction, I certainly thought that hulls were GRP all the way through. I was talking to a Powerboat Instructor who mentioned this method of construction and he was wondering if when a boat hull flexes the outer thin GRP could come unglued from the balsa core and then start to wear with constant flexing.
Time will tell. (But not with my money)
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In many cases, it's the other way around.
Cored hulls are stiffer for the same weight, so flex less and do not suffer from fibre breakage or tearing the fibre out of the resin on the micro scale. Sandwich dinghy hulls have much longer competitive lives as a result.
Of course there is a flip side to this, where a plain GRP hull will dent massively and spring back with only gelcoat crazing visible, a sandwich hull will either bounce off or crush horribly.
I might prefer a rigid foam core to balsa, but some will disagree about that, as end grain balsa is a good core material.
 
Our current boat (1979) has a balsa cored deck, and our 'new' (1976) boat (or rather project!), has also. Both have suffered minor water ingress into the balsa core, due to unsealed fitting of deck furniture, but no serious problems.

On the basis of our experience I would suggest that a balsa cored deck is a perfectly acceptable technology that's fit for purpose, but let down by the ignorance of most DIY owners (and some boatyard bodgers). The manufacturers and, dare I say, the boating press are at least in part responsible for the widespread ignorance of the simple precautions needed to ensure a long life for such decks.

I'd be happy to buy another boat with a balsa cored deck unless it was well gone, which would be readily apparent by excessive and widespread springiness/flexing of the deck.

I wouldn't touch with a bargepole a boat whose decks had deteriorated badly. But for someone more practical than me, and with more time on their hands, it could be a route to a bargain. Reparing extensive rotting of the core is, in principle, a simple job. In most cases it becomes a gruelling task because people usually want to save the appearance of the deck, and therefore have to work on the underside of the deck, inside (limited space, lots of mess) and working above their heads. If it's an older boat where the owner can tolerate a visble join on the deck (or somehow make a feature of it?), working from above would make it much easier.
 
As already mentioned most boats have a balsa core deck - good practice is to cut out the balsa and have plywood or similar inserts in the way of deck fittings etc

Many sailing boats have balsa core in the hull above the waterline too. Aids stiffness and insulation. Some Sadlers and Etaps have them all through the hull.

Nomex honeycomb sandwich construction popular for lighter and more expensive yachts.
 
E39mad said:
As already mentioned most boats have a balsa core deck - good practice is to cut out the balsa and have plywood or similar inserts in the way of deck fittings etc
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When our deck was being restored, I insisted that there should be no fittings through the decks balsa core.
All fittings (cleats, toerail, genoa track, granny bars, ...) go through solid GRP.
 
I would have no problem (and would consider it a good thing) for a new boat to have a core, and probably would be happy going out to 5 years old (and 1 or 2 prior owners)........more than that I would start to be looking for proof that the core is not wet (rather than presuming it is not - unless proved otherwise)........and the older the boat (and more owners) the more fussy I would get.

Obviously price cures most things - but nonetheless doing serious work on wet core is expensive and a complete PITA.

FWIW, as I was in the market for an old boat I stuck with no core anywhere (and accepted the plusses and minuses to that approach).


Core is best when it has no problems.
 
I'm actually surprised to see there are still boats (new models) being developed/produced that have balsa-cored parts. There are plenty of alternatives available these days that are much more useful for boat building. I have a hard time believing that the costs are a significant problem as many of the yards that still use balsa are not the cheapest around.
To me the question of water-ingress in Balsa cored parts is not question of if it happens but when it happens.
 
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