cost of extending the life of a mid 70s fiberglass hull

[Wellington]

With so many fiberglass and plastic coating products on the market its hard to gauge a rough idea of how much per square meter it will likely cost to recover an old mid 70s fiberglass boat with a new layer of fiberglass/resin/polyester/whatever to extend its life. If anyone can give some ballpark numbers and estimates of cost per square meter and how many years such a treatment will extend a boats life it would be greatly appreciated. I'm also interested to hear how old boats usually fail when they come to the end of their life. Is it usually the boats structural wooden frame that fails before the hull or does the hull just become paper thin and spring leeks first? Can a 70s fiberglass boat be patched and repaired indefinitely without too much cost? The reason i ask is i fear buying a 70s boat and then being told it has 1 month to live and there is nothing that can be done that wont cost the earth. What is the worst case diagnosis senario for boats of this age?

Thanks

 

[messabout]

Many a 70s or even older FRP boats have been suitably resurrected. The usual malady is that the wooden or foam parts have deteriorated into an unsatisfactory state. Fiberglass boats almost always have some structural elements that are not fiberglass. In the case of an outboard runabout or similar boat, the transom is suspect. It usually has plywood sandwiched between some relatively thin FRP covering. The plywood becomes waterlogged and rots over time. Same deal with floor stringers that are encapsulated with fiberglass. They absorb moisture, become heavy, and eventually deteriorate, The structural elements need to be replaced.

If you are sufficiently ambitious you can tackle those jobs. Restoring an old glass boat is a most laborious, dirty and itchy process and some expense will be involved. Often enough the expense is more than the boat will be worth. That is a personal call but there have been some marvelous restorations by determined owners.

 

[Mr Efficiency]

I agree with messabout, and I would add that to be a worthwhile restoration, it needs to be a good, proven hull, if the boat was a so-so performer, it is a doubtful proposition at best. Pick a good one.

 

[Wellington]

Many a 70s or even older FRP boats have been suitably resurrected. The usual malady is that the wooden or foam parts have deteriorated into an unsatisfactory state. Fiberglass boats almost always have some structural elements that are not fiberglass. In the case of an outboard runabout or similar boat, the transom is suspect. It usually has plywood sandwiched between some relatively thin FRP covering. The plywood becomes waterlogged and rots over time. Same deal with floor stringers that are encapsulated with fiberglass. They absorb moisture, become heavy, and eventually deteriorate, The structural elements need to be replaced.

If you are sufficiently ambitious you can tackle those jobs. Restoring an old glass boat is a most laborious, dirty and itchy process and some expense will be involved. Often enough the expense is more than the boat will be worth. That is a personal call but there have been some marvelous restorations by determined owners.

lots of good info in that post and exactly what i needed to hear. Thanks. I'm mystified why 8m catamarans from mid 70s are priced starting from 15k and up. Given fiberglass first appeared in the mid century i'm wondering what happens to the value of a mid 70s cat in ten or 20 years from now? Does it just suddenly fall off a cliff and become worthless? Is that why i see very few mid 60s boats on the market?
Kind regards
Wellington

 

[Richard Woods]

I would avoid boats with a balsa core unless you inspect them very carefully. But lots of foam sandwich and solid glass multihulls form the 60's and 70 are still sailing. Usually it is the deck gear/engines/galley/cushions etc that need replacing. The basic hull goes on for ever. That is the big problem with boatbuilding today, and also for marina and boat yard owners. Way too many abandoned boats that still float after 40-50 years. You can find Iroquois, Catalacs, HT's etc for under 10,000 asking price. And they will sell for much less, like half asking price

RW

 

[Wellington]

I would avoid boats with a balsa core unless you inspect them very carefully. But lots of foam sandwich and solid glass multihulls form the 60's and 70 are still sailing. Usually it is the deck gear/engines/galley/cushions etc that need replacing. The basic hull goes on for ever. That is the big problem with boatbuilding today, and also for marina and boat yard owners. Way too many abandoned boats that still float after 40-50 years. You can find Iroquois, Catalacs, HT's etc for under 10,000 asking price. And they will sell for much less, like half asking price

RW

Well that's good to hear and reassuring coming from a boating veteran like yourself (I assume i'm talking to the Richard Woods boat designer and not his admin). I once spoke with James Wharram on the phone who basically told me the same thing and also added it was perfectly safe to sail the atlantic ocean in one of his 20ft cat designs. I don't think however i'll be testing that last part of his theory out any time soon though

Do you know if the stitch and glue method James Wharram used (and maybe yourself too) has changed much over the years? I would be interested to hear a basic description from yourself on how it was done originally, since recent internet info on the stitch and glue method sounds a bit conflicting.

kind regards

 

[gonzo]

Wharrams are are built over bulkheads and stringers, unless they are the really small ones

 

[fallguy]

I would avoid boats with a balsa core unless you inspect them very carefully. But lots of foam sandwich and solid glass multihulls form the 60's and 70 are still sailing. Usually it is the deck gear/engines/galley/cushions etc that need replacing. The basic hull goes on for ever. That is the big problem with boatbuilding today, and also for marina and boat yard owners. Way too many abandoned boats that still float after 40-50 years. You can find Iroquois, Catalacs, HT's etc for under 10,000 asking price. And they will sell for much less, like half asking price

RW

Best advice.

Pay for a survey or throw away money on decent looking trash.

Lots of 70s boats used balsa poorly.

 

[Wellington]

Wharrams are are built over bulkheads and stringers, unless they are the really small ones

my mistake, i thought i remembered James Wharram boats as being stitch and glue. I'm not even sure if stitch and glue is a viable method anymore with the price of marine plywood board in the uk. I'm also not sure if the first stitch and glue boats even used a "marine plywood" grade.

 

[JSL]

Some good advice from all the preceding.
Not sure about the UK but if I have my memory correct, here in north America during the 70's we were dealing with the arab oil embargo. Resin was not in good supply and there were rumors that some may have thinned it out a bit. Polyester resin will absorb a small percentage of water and 'thinning' may have made it worse.

 

[fallguy]

To be clearer, anytime anyone thru hulled a boat or screwed into a boat with balsa improperly since the dates of inquiry; those boats have pretty much all got core rot. So, if it wasn't on poor build practices, it could have been the nearly 50 years of people holing boats and not sealing the cores properly as well. One screw hole might have been all that was required.

It is a serious issue.

See, once a boat gets a dime sized intrusion of water below the waterline; the water starts to get pushed around by hydraulic pressure. Pascoe has a great piece on hydraulic erosion. A dime sized piece becomes plate sized in a hurry and total hull failure follows.

The reason I am adding this point is because you can't overlook any balsa core boats for the issues or even a boat with say glass hulls and cored decks.

Marine surveyors are an absolute must for buying vintage boats.

I purchased a 70s boat about 6 years ago with core rot. I spent $3500 on the boat and disposal and recovered about $1000 in parts. If I had thrown a surveyor $500, I'd be $2000 ahead. My expertise lies in experience. If you pay 10k for a boat; the money you spend on a survey can usually be negotiated in any deal when, not if, the surveyor finds any issue.

If you end up walking away, the cost of the survey is basically purchase insurance.

 

[Wellington]

Some good advice from all the preceding.
Not sure about the UK but if I have my memory correct, here in north America during the 70's we were dealing with the arab oil embargo. Resin was not in good supply and there were rumors that some may have thinned it out a bit. Polyester resin will absorb a small percentage of water and 'thinning' may have made it worse.

In the uk ive heard people say that boats built before about 1975 were made much thicker and stronger because people had to guess how much thickness would be strong enough. As time went on people experimented with thinner and thinner hulls as a way for boatyards to save on costs. Today modern boats are often the bare minimum thickness and some companies use a vacuum bag mold so that not a litre of resin more than necessary is used and it is all precision measured.

regards

 

[fallguy]

Actually, sir, you have confused a few things.

Using too much resin does not result in a stronger boat.

The correct resin to fiber ratio is actually to use very little resin, in general terms.

Solid glass hulls built before the 70s might be heavy and solid, but they might also not float on capsize or a hull breach or thru hull failure. Keep that in mind. As is often the case with boats; one thing glittering does not make the boat gold.

Hopefully, someome smarter than me can finish this with better remarks.

 

[Wellington]

Actually, sir, you have confused a few things.

Using too much resin does not result in a stronger boat.

The correct resin to fiber ratio is actually to use very little resin, in general terms.

Solid glass hulls built before the 70s might be heavy and solid, but they might also not float on capsize or a hull breach or thru hull failure. Keep that in mind. As is often the case with boats; one thing glittering does not make the boat gold.

Hopefully, someome smarter than me can finish this with better remarks.

I would bet that it is not strength and quality that motivates the boat building industry to vacuum bag boats and use very little resin despite what the brochures say. I would go with my hunch that many old boats were simply over engineered and boatyards are under pressure to find a compromise between strength and cost of resin.

 

[fallguy]

I would bet that it is not strength and quality that motivates the boat building industry to vacuum bag boats and use very little resin despite what the brochures say. I would go with my hunch that many old boats were simply over engineered and boatyards are under pressure to find a compromise between strength and cost of resin.

You will get a better response, but consider for a moment a brick. All clay and the brick has nothing binding it together and fractures easily. All straw and the brick is weak.

Modern composites have been tested and retested and the resin to fiber ratios are much better understood.

In general terms; more resin is not favorable.

Vacuum bagging results in removing resin from the laminate to increase the fiber ratio in a layup. It is not done to maximize resin.