Thick Antifoul

[auriga]

River Quays Marina at Mortlake (just up the river from where you were moored - near the car ferry there)

[Joe]

Greeting to all

Could anyone help regarding checking for osmosis on an old mark1

I’m thinking of purchasing the above, if I can convince the owner to put her on the dry (at my expense) for 24 hours.Would I be able to observe any possible osmosis problems through 4 years of growth?

If I used a high pressure hose would that be enough to gain a window into possible osmosis issues or would I need to scrape for 3 days before gaining a real look at the hull.

Could someone also tell me what to look for? Is there such a thing as manageable osmosis? What would be regarded as tragic etc? Do these hulls have a life span? 30 plus years seems old for a plastic boat?? As you can see I’m totally in the dark….

Alert and Alarmed novice

[Miker]

Welcome Paul,

I'm by no means an expert here, but I understand what you're worried about.

From what I have been told by an independent ex-shipwright, osmosis on a full glass boat is no where near as bad as a boat that is made of sandwich core or laminates. (Others correct me if I'm wrong)

My boat has some small blisters that it had when it was inspected in 2005. According to the marina who did the last three years worth of anti-fouling, they hadn't changed. Their recommendation was to leave them until they changed shape or size, or if budget allowed, get them repaired. There are about half a dozen about 6 cm diameter on the keel itself.

30 years old isn't that old for a glass boat, providing it's been reasonably well looked after. If you're really worried, you should spend the extra and get it checked on the hard by a qualified shipwright. You'll need to do this for insurance anyway, so whilst it's expensive, it's also good for peace of mind.

If you were going to slip it and look it over yourself, how hard they are to see would depend on the condition of the hull and how much growth there is... if there is a lot of growth it's a more daunting prospect, but if it's recently slipped you'll have no real problems.

As I said, if you're a worried novice, get a professional, it will still be cheaper than trying to offload a boat that in the end won't be suitable to be repaired.

Michael

[auriga]

Welcome to the site,

Through four years of growth it would be probably impossible to tell unless it was in a catastrophic condition. If its just slime with light shelling it probably wouldnt be too hard, but years of growth doesnt sound encouraging!

All osmosis is manageable, its the expense associated with fixing it that is the deciding factor. It would be the exception, not rule to find a 30 year old glass boat without a hint of osmosis in her somewhere to some extent.

Small (size 5 - 20 cent coin ) blisters in isolated areas here and there isnt too much of a problem, but if the boat looks like she has a case of chicken pox with many many small blisters over her, or major delamination you're best to walk away.

My mark 3 is around the 30 years old mark and after inspecting a month of so ago when on hardstand, she has maybe half a dozen or so small blisters here and there. I discussed with the shipwright and their opinion in my case was that given the age of the vessel, if osmosis was going to wreck her, she'd have sunk many years ago now.

Blisters are fairly easy to spot, they bubble out from the rest of the hull, you may see some seepage of water from them when the paint drys out a bit. Take care not to pop them without adequate eye protection, the water inside can turn to an acid and there can be a buildup of pressure in the blister.

A good surveyor will give you the low down on the condition, expected costs to repair etc

As Michael said, if you're going to be insuring the boat you will need an out of water survey. A survey will cost up-to about $1,000 and really is money well spent as they'll go over the boat from bow to stern. If there is a rigger at the slip, ask them to have a quick look at the rig and get their thoughts (note any rigger will tell you that if the rig is more than 5-7 years old it needs replacing) but you may be able to get away with the current rig for a while yet depending on its condition and your intended usage.

Where is the boat located?