When to plan for a hull replate

[DeanS]

Hello all.

 

In 2007 my boat had a survey, and thicknesses showed to be fine for it's age, with "years of use" still ahead. I'm planning on getting it out in July and blacken it with 4-5coats, but I've adopted a "head in the sand" attitude towards the hull thickness.

 

BUT...

 

At some point in the future, I am happy to consider replating. I had to cut a cold cupboard from the boat with a grinder a while back, and found the metal to be really hard...it took me hours to cut it out.

 

How would I know replating was getting urgent......I doubt the boat would suddenly have a breach ...surely it would perhaps spring small leaks first....dont you think? ...

 

I am tempted to think that many of you out there have no plans to ever get your hulls surveyed, and "like me" will watch for holes?

 

Lastly...a full replate is probably a few thousand pounds....so would it be ok to replate only along the corrosion spots?

 

?

[bottle]

Totally flippant answer so please ignore

 

How would I know replating was getting urgent

 

When on board your feet are wet.

 

Slightly better answer

 

The only way is to have it examined when ever it is removed from the water, regular blacking will/should delay.

 

There are so many variables that a definite time scale is impossible.to predict.

 

If there are some thin points they can be 'weld filled' before plating is necessary.

 

Age of boat, original thickness, thickness now,maintenance etc. will affect the time scale.

 

There are many very old boats out there that have never been plated and were built with thinner steel than now.

[koukouvagia]

Most insurance companies demand a full hull survey when boats reach a certain age. The interval between surveys seems to vary – I have to do mine every ten years. These surveys may seem expensive, but a thorough going over of the hull is very re-assuring. I've just had a full hull survey on the butty and there were five small weak spots and one or two dodgy rivets that needed seeing to.

This hasn't really answered your question, though. Sorry.

Edited December 21, 2010 by koukouvagia

[alan_fincher]

Hello all.

 

In 2007 my boat had a survey, and thicknesses showed to be fine for it's age, with "years of use" still ahead. I'm planning on getting it out in July and blacken it with 4-5coats, but I've adopted a "head in the sand" attitude towards the hull thickness.

Provided you follow usual guidance about blacking and replacing anodes, I personally would say start to worry about it either about 2027, (i.e. boat 20 years old), or when your insurance company show an interest, (whichever comes first).

 

That's not meant to be flippant - you have effectively a near as new boat.

 

I doubt many would advocate as many as 4 or 5 coats of blacking. I'd say the relative benefits of going more than 3 are unlikely to outweigh benefits and costs.

 

Then of course you can get into the debate about whether you plan to try and black the bottom plate itself!......

[canaldrifter]

 

 

There are many very old boats out there that have never been plated and were built with thinner steel than now.

 

 

I'll vouch for that, although it does also depend on the quality of steel used in the build.

 

I don't think newer boats built of Polish steel are going to last as long as some old Springers built of much thinner second-hand gas holder steel.

 

Tone

[DeanS]

Provided you follow usual guidance about blacking and replacing anodes, I personally would say start to worry about it either about 2027, (i.e. boat 20 years old), or when your insurance company show an interest, (whichever comes first).

 

That's not meant to be flippant - you have effectively a near as new boat.

 

I doubt many would advocate as many as 4 or 5 coats of blacking. I'd say the relative benefits of going more than 3 are unlikely to outweigh benefits and costs.

 

Then of course you can get into the debate about whether you plan to try and black the bottom plate itself!......

 

 

My boat isnt new. It's a 1985 boat...but had it's last survey in 2007...which showed most plates about 4mm . I suspect it was 6mm when built. Thus...4-5coats in July..just in case. I may wait for my insurance to shout at me before a new survey.

[alan_fincher]

My boat isnt new. It's a 1985 boat...but had it's last survey in 2007...which showed most plates about 4mm . I suspect it was 6mm when built. Thus...4-5coats in July..just in case. I may wait for my insurance to shout at me before a new survey.

My abject apolodies, Dean.

 

Completely misread your post!

 

I would blame the cataract for which I am still awaiting a surgery date, but I suspect I've used that excuse at least once too often.

 

Ignore my ramblings, then!

[canaldrifter]

My boat isnt new. It's a 1985 boat...but had it's last survey in 2007...which showed most plates about 4mm . I suspect it was 6mm when built. Thus...4-5coats in July..just in case. I may wait for my insurance to shout at me before a new survey.

 

Good idea.

 

Tone

[MoominPapa]

On the subject of insurance companies wanting surveys. Melaleuca will be 20 years old next year, so it's possible the insurers will want a survey. Are they likely to accept the survey we had done at purchase, three years ago, or will they want a new one? Presumably if they want a survey every ten years, they'll be happy with a 2007 survey until 2017?

 

MP.

[Keeping Up]

My insurer asked for a survey at 15 years. At 14 years we asked "are you sure" and they said "no, 20 will be fine". Then as we reached 19 years, the policy magically changed to not require it until 25 years. I'm not complaining!

[koukouvagia]

On the subject of insurance companies wanting surveys. Melaleuca will be 20 years old next year, so it's possible the insurers will want a survey. Are they likely to accept the survey we had done at purchase, three years ago, or will they want a new one? Presumably if they want a survey every ten years, they'll be happy with a 2007 survey until 2017?

 

I found my insurance company most accommodating. They were prepared to defer the hull survey for a couple of years so that it would coincide with the BSS.

[bottle]

It's a 1985 boat...but had it's last survey in 2007...which showed most plates about 4mm . I suspect it was 6mm when built.

 

So if it was built with 6mm steal and it has lost 2mm in 25 years, then......................................you may not need to worry.

 

Lots of boats started out at 4mm.

 

The old timers experts on here will know when the 'standard' changed to 6mm for the hull sides.

[canaldrifter]

I think he's on about the bottom plate.

 

Tone

[JGMarine]

My boat isnt new. It's a 1985 boat...but had it's last survey in 2007...which showed most plates about 4mm . I suspect it was 6mm when built. Thus...4-5coats in July..just in case. I may wait for my insurance to shout at me before a new survey.

 

4mm is the minimum thickness an insurance company will accept on fully comp insurance. Any thinner and it will need overplating as its classed as uninsurable.

 

You will need more than a few thousand for a full overplateing job.

 

If you are insured fully comp i would wait till the insurance co asks for a survey.

[alan_fincher]

4mm is the minimum thickness an insurance company will accept on fully comp insurance. Any thinner and it will need overplating as its classed as uninsurable.

As some of the more lightweight Springers were built from new with steel no thicker than 4mm, does that then mean that as soon as they have lost any steel at all, they became uninsurable, then ?

[MoominPapa]

I had to phone the insurance co. this morning to ask where the renewal was ("in the post" of course!) so I asked what the policy was on surveys. The answer is that they will never ask for a survey for policy renewals. As long as cover is continuous, the boat can be any age and no survey is required. I imagine they'll ask for a survey before taking on an older boat, but that wasn't relevant so I didn't ask.

 

This is Haven Knox-Johnston, BTW.

 

 

MP.

[canaldrifter]

I had to phone the insurance co. this morning to ask where the renewal was ("in the post" of course!) so I asked what the policy was on surveys. The answer is that they will never ask for a survey for policy renewals. As long as cover is continuous, the boat can be any age and no survey is required. I imagine they'll ask for a survey before taking on an older boat, but that wasn't relevant so I didn't ask.

 

This is Haven Knox-Johnston, BTW.

 

 

MP.

 

Same as mine. Nautical Insurance Services Ltd underwritten by LLoyds.

 

Tone

[KeithL]

How would I know replating was getting urgent......I doubt the boat would suddenly have a breach ...surely it would perhaps spring small leaks first....dont you think? ...

hi, your right, you will probably get small leaks from a few pits in the steel getting really deep and then letting a small amoumt of water in through very small holes. not good, but your boat is unlikely to sink overnight, but if you've ever had a dripping tap you will know that its surprising how much water is in the sink the next day ! good luck, although im sure it'll be fine

Edited December 22, 2010 by KeithL

[mayalld]

hi, your right, you will probably get small leaks from a few pits in the steel getting really deep and then letting a small amoumt of water in through very small holes. not good, but your boat is unlikely to sink overnight, but if you've ever had a dripping tap you will know that its surprising how much water is in the sink the next day !

 

I suspect that you are wrong.

 

The thing with hulls getting thin is NOT that they eventually reach zero thickness and start to weep.

 

The more usual mode of failure is that eventually an area is sufficiently thin that it fails when subjected to mechanical forces, leaving a sudden BIG hole.

[RLWP]

I suspect that you are wrong.

 

The thing with hulls getting thin is NOT that they eventually reach zero thickness and start to weep.

 

The more usual mode of failure is that eventually an area is sufficiently thin that it fails when subjected to mechanical forces, leaving a sudden BIG hole.

 

From what I've seen of our hull wear, there will indeed be a big hole, and it will be along the welded seam between the baseplate and sides. That's where our baseplate had become thin

 

Richard

[KeithL]

I suspect that you are wrong.

 

The thing with hulls getting thin is NOT that they eventually reach zero thickness and start to weep.

 

The more usual mode of failure is that eventually an area is sufficiently thin that it fails when subjected to mechanical forces, leaving a sudden BIG hole.

Possible, but he wasnt asking about impact damage.

[koukouvagia]

From what I've seen of our hull wear, there will indeed be a big hole, and it will be along the welded seam between the baseplate and sides. That's where our baseplate had become thin

 

How common an occurrence is it for rivets to fail? I've just had a few welded up on the butty but I'm not sure whether it was necessary or not.

[Keeping Up]

How common an occurrence is it for rivets to fail? I've just had a few welded up on the butty but I'm not sure whether it was necessary or not.

 

There was a boat that sunk in Milton Keynes marina when we were there 15 years ago, because when the water froze it popped a few rivets. Presumably it got behind their heads, or between the plates.

[DHutch]

My insurer asked for a survey at 15 years. At 14 years we asked "are you sure" and they said "no, 20 will be fine". Then as we reached 19 years, the policy magically changed to not require it until 25 years. I'm not complaining!

Ours asked for one at 15, got one, and then asked again at 20. We suggested they looked at the previous survay, in partiucular the line that reads to the tune of 'this boat exhibits zero wasting of the hull' and that we could send them photos of the last drydock. So far nothing back.

 

The answer the OPs question, I would never plan for overplating if i could help it.

 

If its sporatic pitting down to 4mm then i wouldnt worry much as that will be failure by weeping and i would just get good paint on it. If its overall thining, just keep an eye on it, what does the hull look like when it comes out?

 

If its caked in rust then you have an issue with you paint process. If not, your not lossing metal. Simples.

 

I would also echo the suggestion that more than three coats is not nessaray or even benifical, spend the time on prep to make sure the first coat sticks beucase if it doesnt the number that follow it is errelvent! We put on two every four years and get no rust.

 

If you getting rust when i comes out and you want to throw a few grand at the hull, i would spend it on gritblasting it back to right and getting a good paint system on it.

 

 

Daniel

[Timleech]

As some of the more lightweight Springers were built from new with steel no thicker than 4mm, does that then mean that as soon as they have lost any steel at all, they became uninsurable, then ?

 

The 4mm figure seems to me to be a rather spurious one, but some surveyors and some insurers do appear to treat it as a magic number below which all life will end.

 

A fairly inexperienced surveyor was 'doing' a small Springer on my dock last year, and was going round 'tut-tutting' at how much replating was going to be needed because all his ultrasonic readings were around the 4mm mark. He was decent enough to revise his approach when he was persuaded to find an unscathed bit of plate to check, it had indeed been built from 4mm plate and was quite tidy for its age. Some of the early small (30' or less) Springers were actually built from 1/8" plate (3.2mm), though I don't think there are many of those left now. I did see a boat not long ago which was actually two of these stuck together to make a longer boat. It was a little while before it dawned on me why that one was quite so thin!

 

 

Tim