Cost of Dealing with Osmosis

[Babylon]

Looking at buying a 1970s 30 footer which has blistering on the hull. Not overly concerned, as the rest of the boat is pretty sound, plus she's a long-keeler with heavily laid-up thick GRP. If I bought the boat, I'd like to have this effectively dealt with at an early opportunity by a professional yard, but I've as yet got no idea of the sort of cost involved.

As I understand it, the process consists of (not sure of the exact order):
1. bleeding (or grinding out?) the blisters
2. drying the hull (naturally over a period of time or faster with with infra-red heaters?)
3. applying epoxy
4. applying gel-coat?
5. applying primer and antifouling

I'd also probably have the topsides re-done at the same time, as they're beginning to look a little tired.

I'm also (if the budget stretches) considering copper-coating instead of traditional antifouling.

IE this is a boat I'd like to keep and bring up to top quality over time, so I'd like to start by dealing with the hull first as my major expense then work on the rest as-and-when.

Any ideas of the sort of cost of this work, and any reccomendations for good yards which could carry out this work on the South or South-West coast?

Thanks

Babs

 

[Topcat47]

£2000 - £4000 depending on how wet the hull is and which yard you use.

Add another £1-2000 for topsides painting, perhaps even more if a lot of preparation is required.

PM me if you're thinking of ant specific yards and if appropriate I'll let you know of my own experience.

 

[oldsaltoz]

You could be burning capital here, the chances of getting any return on the money spent must be very close to zero.

If you must do this, look for a place to stand your boat other than a regular hardstand and either do the work yourself or at least do the bulk of the preparation, this will save you squillions.

A few years ago a friend wanted to do much the same as you, osmosis treatment and full topsides and deck paint.

We found a spot on a riverside property and organised a crane to lift her out. the owner of the land charged him a piddling amount per month and included power and water, the only condition was that the block be kept tidy (mow the grass).

We peeled the hull using a standard power planer with the corners of the blades rounded and a grinder fitted with a concrete grinding disc, then ground out all the signs of osmosis and left to dry after washing them; the washing was repeated every few weeks right after moisture readings were recorded.

During this drying period the preparation of the topsides and deck were completed and a primer applied then sanded. A professional spray painter was appointed and the spray painting was completed in under 2 hours. All masking, scaffolding and clean up was done by us, the painter only had to spray and clean his own gear.

To dry the hull we used a combination of heaters and heat lights, focused on the high moisture areas from the inside the hull so the treatment of the osmosis was started as soon at each area had reached a pre set moisture level leaving more drying power available for other areas.

When the hull repairs were completed, we applied a layer of cloth and covered that with a layer of rovings then faired the below water area and applied another 5 coats of epoxy resin; high build epoxy primer was applied over this and sanded prior to antifouling.

All in all a very satisfying project and at a mere fraction of the cost quoted plus the added bonus of knowing that no short cuts or shoddy work had been included.

Hope this helps.

Avagoodweekend......

 

[charles_reed]

My 31' would have cost around £7000 for grinding off and replacing the gel coat, epoxy-shielding and re-antifouling, if the blisters had proved to be more than superficial.

These prices were quoted me 2 years ago in Malta where:-

a) wages rates were considerably lower than UK
b) the climate was far more conducive to drying

As it so happened they were not significant, easily filled and, after having all the old antifoul taken off, the boat was give 6 coats of gel-shield and re-antifouled for 1/3rd the price.

Let's hope your blisters turn out to be as unimportant.

Most of the cost lies in the man-hours involved and the suggestion of doing it yourself has real merit.

PS A fortnight after being taken out this summer she was surveyed and found to be moisture free.

 

[jason -and the arguenauts]

They were trying to rip you off in Malta, Charles. Cost to the previous owner of the osmosis job on my 33 ft cat was £3500 including complete peel of gelcoat, months in shed and West epoxy. Juts done my current 36ft mono (dry so didnt need peeling but with some existing hard barrier coat that took 2 men 4 days to shift) at a cost of £3075

I would never advise anyone to buy a boat with the pox. Three reasons - firstly the epoxy coat isnt a pemanent cure./ Even epoxy is permiable to some degree so the problem will return. Second, the treatment can take a lot of time and you can lose a complete season if you're unlucky. Thirdly the cost which you wont recover.

 

[Babylon]

Thanks for the helpful info

Thanks people for the good advice. I'd rather avoid buying a boat with anything more than superficial blistering (if any at all), but if I do proceed with this particular boat (extent of problem not yet known and price therefore subject to negotiation) then at least I know what the processes, costs and time out of commission are likely to be.

Cheers

Babylon

 

[Tranona]

Many yachts built in the period you are looking at will have osmosis, so it is difficult to avoid it. Howeverr with heavy solid GRP laminates it is unlikely to be a structural issue. One of the reasons for osmosis is poor curing in heavy laminates and poor by today's standards gel coats.

As you have already discovered there are many ways of "treating" the problem varying from leaving alone to complete stripping and re finishing usually with an epoxy. You can even have the gel coat on the topsides replaced rather than spraying. There have been many articles in the mags - a long series a couple of years ago in PBO which are worth reading so you are up to speed with the topic. Then employing a surveyor who specialises is worth it if you suspect a serious problem.

You are in a bit of rock and a hard spot as most of the old fashioned style boats you are looking at were made in that period and have low values - partly because of potential on going problems. If you are going to keep such a boat for a long time you could have to apply treatment more than once, which could cost 25+% of the value of the boat!

Unless you are absolutely wedded to old fashioned style boats and are prepared for a lot of ongoing (DIY?) maintenance, you might be better looking at more modern boats. Remember that long keel heavy displacement boats are now a real minority interest and thousands of families happily cruise in fin keel boats - many of us even in AWBs. On your budget you have a pretty good choice of modern boats, and I think once you have tried them you (and your family) won't want to go back.