Should I have her grit blasted, dried and epoxied?

[Mike Bryon]

The boat I’m buying is balsa cored except around keel and through hull fittings where she is sold epoxy. She has high hull moisture readings but no evidence of structural damage/rot/delamination.

Owner’s survey 2024 says moisture levels commensurate with age of vessel (38 years) no recommendations made. My survey says risk of future structural damage resulting from presence of moisture, monitor levels annually. Meter reading on both surveys are pretty much the same.

I’m inclined to spend 8/9k getting her dried and epoxied. Not content with option of leaving alone as should rot or delamination of core occur the fix is crazy/ give the boat away/ expensive.

Am I being over cautious?

 

[RunAgroundHard]

I have an older GRP boat from 73 build, 74 launch. GRP decks and hull, balsa core coach roof, so a bit different to you. Moisture readings in hull were high at survey, in some spots, but they were taken on a hoist lift, hold and launch again, service on a during wet day. I did not have any faith in them. However, survey stated the same, commensurate with age.

Years later, I have been surveying moisture and it alternates between high and low, depending on how dry the winter has been and location of vessel, exposed to sun or dank corner of yard. There has been no change in vessel integrity as far as I can tell. The previous owner did lightly sand blast back to clean gell coat and applied one of the propriety barrier coats about 20 years ago. Hence that may have worked. If I remember correctly, they just air dried the hull over the winter and then had the coating applied in the spring, summer.

My advice, if there's no Osmosis noted, do not do anything. If there is small osmosis, prick, drain and fill individually any blisters.

There is a very real risk that drying the hull will not work. The water molecules pass through the GRP and react with uncured chemicals in the resin and make compounds that are larger and can not pass through. Therefore air drying does not work, unless a hot vacuum process is used. Not worth it in my view. Any water molecules that have not reacted will continue to pass through the hull and dry out.

Good luck with you decision. I think you may be over cautious but difficult to say. Water damage to the balsa core if balsa is in the hull layup, is something to be very worried about. I would want to understand if that balsa core was damaged by water ingress.

Thats how I see it as an amateur, with an old boat that has been refurbished. Happy to be corrected.

 

[Fr J Hackett]

Have you thought about not buying it.

 

[SailingDog]

An interesting situation, do you have any options to get her under cover and let drier weather bring the moisture down over time ? Ideally you need a friend with a hay shelter with a roof and no sides.There could possibly be issues if you dry her out too quickly, you would have to balance not being able to use her against cost obviously if you go au natural.

 

[Tranona]

Difficult decision without knowing the history of moisture readings. It could be that it has been high for years with no indication of any damage. The complete strip dry epoxy route is not always a guaranteed success and you could lose the use of the boat for a longish period while it dries out. depending on what your future plans are maybe the monitoring recommendation is sound. However if you do go down the full fat route suggest you Coppercoat at the same time.

 

[SailingDog]

Have you thought about not buying it.

Spot on FJH I missed that, there are lots of older boats for sale.

 

[jwilson]

An interesting situation, do you have any options to get her under cover and let drier weather bring the moisture down over time ? Ideally you need a friend with a hay shelter with a roof and no sides.There could possibly be issues if you dry her out too quickly, you would have to balance not being able to use her against cost obviously if you go au natural.

Just drying does not do that much. It takes moisture many years to get in through the gelcoat, and probably many years to get out again unless the gelcoat is removed. Being ashore dry in winter is good, but don't expect miracles in moisture reduction to laminate or core.

 

[Fr J Hackett]

If a balsa cored boat has water in the balsa core then the core even if it's not showing damage now especially if it has true high moisture levels, then it is very likely that the core material will be damaged and the cure will be replacement or better still walk away.

 

[Bajansailor]

The boat I’m buying is balsa cored except around keel and through hull fittings where she is sold epoxy.

Is this a class of vessel, with various others built in the past, or a 'one off' build?

You mention that the single skin areas in way of the keel and the through hull fittings is 'solid epoxy' - does this mean that the whole hull was built with epoxy resin, rather than fibreglass?

Have you or your surveyor carefully tapped all over the hull with a hammer to see if you can find any areas of delamination (which would be a strong indicator of the core rotting behind the fibreglass)?

 

[Mike Bryon]

My last boat I epoxied in the Caribbean. She dried fast in a great big concrete yard and the labour and epoxy was great value!

Two surveyors have hammered/tapped away and report no delamination/signs of rot on this current boat. But the only way to know for sure would involve taking core samples! There were only 12 built in the class by reputable UK yard. I understand that she is fibreglass with solid epoxy in high stress/through hull areas The quote to dry her involves grit blast then vacuum heated pads. I would employ the surveyor to confirm dry readings before agreeing epoxy’s applied. The yard has said it will take a good while to dry in their shed because balsa cored.

As for the second-hand market, I’ve found it not so flush with the type of boat I’m trying to buy. This is my third attempt. The first I offered 2K below the asking price and the owner withdraw it from the market. Number 2 was for sale approaching 3 years only for another buyer to pop up and offer 3k more than my offer. There are other buyers lined up for the current boat.

I plan to buy her but must decide if I dry and epoxy or monitor. To give a flavour of what I’ve been looking for: bal/disp +40, capsize formula -2, moderate bluewater, high performance. Not so many fit the bill.

 

[Bajansailor]

I understand that she is fibreglass with solid epoxy in high stress/through hull areas

So does this mean that the whole hull is built using epoxy resin with glass cloth to form the inner and outer skins sandwiching the balsa core?
Or are there localised areas of solid epoxy and mat in way of the high stress areas and the through hull fittings, and the rest of the hull is fibreglass with polyester resin?

The yard has said it will take a good while to dry in their shed because balsa cored.

I think it would be virtually impossible to properly dry the core (if it is wet) even if you use 'vacuum heated pads' on the exterior of the hull.

 

[Mike Bryon]

Sorry for being unclear. I understand her to be fibreglass inner and outer skins sandwiching balsa core except for high stress and through hull fitting areas where the fibreglass inner and outer skins sandwich solid epoxy core.

As you say ‘if’ she is wet she will be hard to dry. Yard does not say impossible but I respect your view.

They claim to treat balsa core by running the heated vacuum pads at 80-90 degrees rather than the usual 130 to avoid damage to the bonding between skins and core. That it takes much longer. The boat Is known to them, they’ve previously done extensive work to her. They sound confident and offer 5-year guarantee but not yet established what they are guaranteeing!

Decisions, decisions

Thanks everyone for views so far.

 

[Supertramp]

At 38 years and with evidence of high moisture in hull balsa coring I would be very wary. Endless debate on here about old and new construction techniques but it is clear that remedies are expensive. At that age simple solid fiberglass for the hull is a good bet.

I would have to really want that specific boat and to be prepared to spend money I would not recover to get it right.

Which is not unreasonable and many owners do similar but wants thought through.

 

[Lightwave395]

I've had three balsa cored boats, including my current 34 year old one.

I've found there are some surveyors out there that don't seem to understand the build type. I have the hull of my current boat surveyed every 5 or 6 years just for reference, it's always had a small amount of damp but both surveyors I've used have insisted it's not a problem and in the case of an older boat it should just be 'managed' and ideally out of the water for a few months every year if possible. the last survey - 4 years ago - apart from one tiny area around one of the deck mounted compasses it hadn't changed so a small amount of epoxy foam fixed it and there was nothing to report that in his view would mean he'd advise any prospective buyer not to buy it.

Back in 2003 the sale of my then 10 year old J44 fell through because a surveyor announced there was damp in the core and it would need a substantial amount of work to remedy. I spoke to another very well known surveyor who had specialist knowledge of balsa cored boats, had studied the methods in detail and who came to look at the boat (it was for sale at Berthon) He pronounced the previous survey as nonsense, the next prospective buyer used him and the sale went ahead with a small, half square metre area of damp that was fixed by Berthon.

I don't worry a lot about it, three surveyors have told me my current boat will likely still be afloat after I've sunk...

 

[Motor_Sailor]

I agree with Lightwave 395. The number of experts who can advise you with either a diagnosis or a cure are vanishingly rare.

It is highly unlikely that a moisture meter dabbled around on the surface is going to identify moisture in the core in isolation. And if moisture has managed to globally penetrate the epoxy skins over 38 years, how long do you plan to leave the drying process for it to reverse? Most core problems (that give balsa its bad reputation) are usually local penetrations around badly sealed fittings.

These 'wet core diagnoses' and the associated doom-mongering are often the impasse to boats being sold. But there is a simple technique to resolve matters, which might sound drastic and does require the cooperation of the seller. But it is in their interest to also establish the true condition of their boat or it will probably remain unsold: You identify the 'wettest area' of the bottom as found by the surveyor. Then use a three inch hole saw to cut through only the outer laminated skin. Then pry the cut disk from the core getting a good sense of the 'effort' required to do this. Examine the inner to face of the disk to see if it came away from the core by failure of the skin / core bond or with in the core itself. Now examine the core (smell, rigidity, moisture levels and then, if concerned about the integrity of the inner skin / core bond, dig the core out and check.

If, as is normal, everything is mechanically bonded and the balsa is less than 10-12% moisture level, grind the edges of the hole back, bed a new disk of balsa core in thick epoxy and laminate the outer skin back to the original schedule. The whole process should take more than 4 man hours so is not a significant cost set against the difference in value between a 'suspect' boat and one with a proven provenance.

 

[Elessar]

Just drying does not do that much. It takes moisture many years to get in through the gelcoat, and probably many years to get out again unless the gelcoat is removed. Being ashore dry in winter is good, but don't expect miracles in moisture reduction to laminate or core.

Quite right. Drying is for wooden boats. The only way to dry a GRP boat is to peel the gelcoat off.

 

[CAPTAIN FANTASTIC]

You dont say the make of the boat so it is difficult to judge. In my opinion it is a lot of work and a lot of money for a boat of that age; just keep an eye on it as it is very unlikely to get worse and enjoy the sailing.