is my boat going to sink?

[Wittenham]

I don't think so, but interested in the views of the CW collective.  The boat was last lifted, examined and blacked in 2018, all was fine.  I don't recall the depth of steel but it was well within tolerance.

 

Obviously, these strakes are above the waterline so they are not going to sink the boat, but what do they say about the state of the hull?  How much work to repair?

 

thanks in advance

[Alan de Enfield]

 

 

Yes, it will sink, but, probably not today.

[frangar]

4 minutes ago, Wittenham said:

I don't think so, but interested in the views of the CW collective.  The boat was last lifted, examined and blacked in 2018, all was fine.  I don't recall the depth of steel but it was well within tolerance.

 

Obviously, these strakes are above the waterline so they are not going to sink the boat, but what do they say about the state of the hull?  How much work to repair?

 

thanks in advance

That’s the issue with just tack welding the rubbing strakes. There’s a new widebeam here that you can watch the rust forming as the rubbing strakes are just tack welded top and bottom. It costs a few quid more to seam weld them when the hull is being built but as you’ve found it saves a lot of pain later on. 
 

Best thing is get the boat out the water. Grind the welds to get them all off. Shot blast the hull. Then seam weld them back and two pack the hull. Not cheap…you will need to see what insulation has been used as that might try to catch fire etc. 

[Feeby100]

The strakes have just been spot welded which I hate as water get behind and rots

but that has no bearing on your hull really 

[Wittenham]

Just now, frangar said:

That’s the issue with just tack welding the rubbing strakes. There’s a new widebeam here that you can watch the rust forming as the rubbing strakes are just tack welded top and bottom. It costs a few quid more to seam weld them when the hull is being built but as you’ve found it saves a lot of pain later on. 
 

Best thing is get the boat out the water. Grind the welds to get them all off. Shot blast the hull. Then seam weld them back and two pack the hull. Not cheap…you will need to see what insulation has been used as that might try to catch fire etc. 

 

thank you, and the insulation is spray foam.  Can I assume that problem is localised to the strakes?

1 minute ago, Feeby100 said:

The strakes have just been spot welded which I hate as water get behind and rots

but that has no bearing on your hull really 

ah. that is the answer i was looking for!  Thank you.

[frangar]

5 minutes ago, Wittenham said:

 

thank you, and the insulation is spray foam.  Can I assume that problem is localised to the strakes?

ah. that is the answer i was looking for!  Thank you.

The trouble with spray foam is whilst it shouldn’t catch fire it will melt and leave you with cold spots…however ripping out all the fit out is also a massive job to do it properly. 
 

Id be slightly concerned for any of the strakes that go under the water as the corrosion might be worse behind them. I’d be looking to get it out the water when you can and find a decent surveyor to have a poke around. 

[Feeby100]

Just inspect where the where spot welded as that be the bad bit on you hull 

if you say the boat was inspected 2 year ago

[Alan de Enfield]

2 minutes ago, Feeby100 said:

Just inspect where the where spot welded as that be the bad bit on you hull 

if you say the boat was inspected 2 year ago

 

2022 - 2018 = 4 years

[Tony Brooks]

14 minutes ago, Feeby100 said:

The strakes have just been spot welded which I hate as water get behind and rots

but that has no bearing on your hull really 

 

Technically I very much doubt they have been spot welded, but as said they have been tack welded here and there, as have most budget hulls.

 

As rust expands to about 8 times the volume of the steel affected the rust can  build up a considerable force to push the straks off the hull or in the case of windows the frame for the cabin side.

[MtB]

26 minutes ago, Wittenham said:

How much work to repair?

 

Quite a bit I'd suggest. This is one of the ways a cheap hull is made cheap. Welding is EXPENSIVE. The rule of thumb when I worked in an engineering firm was a skilled welder was expected to weld a inch per minute. And ISTR a cost rule of thumb being £1 an inch but this was decades ago.

 

So measure the length of all the guard irons on your hull then you can work out some times and costings to weld them on properly. i.e. continuously along the whole length of every rail, top and bottom. 

 

Then there is removal, cleaning up and prep work of the old rails before any welding gets done....

 

 

[frangar]

28 minutes ago, MtB said:

 

Quite a bit I'd suggest. This is one of the ways a cheap hull is made cheap. Welding is EXPENSIVE. The rule of thumb when I worked in an engineering firm was a skilled welder was expected to weld a inch per minute. And ISTR a cost rule of thumb being £1 an inch but this was decades ago.

 

So measure the length of all the guard irons on your hull then you can work out some times and costings to weld them on properly. i.e. continuously along the whole length of every rail, top and bottom. 

 

Then there is removal, cleaning up and prep work of the old rails before any welding gets done....

 

 

And the possible work inside….it amazes me that people will pay for a superficially flash fit out on say a collingwood widebeam but not have the hull welded properly. 

[Wittenham]

1 hour ago, MtB said:

 

Quite a bit I'd suggest. This is one of the ways a cheap hull is made cheap. Welding is EXPENSIVE. The rule of thumb when I worked in an engineering firm was a skilled welder was expected to weld a inch per minute. And ISTR a cost rule of thumb being £1 an inch but this was decades ago.

 

So measure the length of all the guard irons on your hull then you can work out some times and costings to weld them on properly. i.e. continuously along the whole length of every rail, top and bottom. 

 

Then there is removal, cleaning up and prep work of the old rails before any welding gets done....

 

 

 

Thank you for the comprehensive reply.  Given that the boat does not have an engine and only gets moved from its permanent mooring site for lifting/blacking, is there a downside to simply taking them off, making the surface smooth and repainting?

[MtB]

3 minutes ago, Wittenham said:

 

Thank you for the comprehensive reply.  Given that the boat does not have an engine and only gets moved from its permanent mooring site for lifting/blacking, is there a downside to simply taking them off, making the surface smooth and repainting?

 

Probably not actually! Other than it will make the boat look a bit weird. 

 

[Wittenham]

1 minute ago, MtB said:

 

Probably not actually! Other than it will make the boat look a bit weird. 

 

 

I believe that is considered a feature at Agenda 21....

[frangar]

5 minutes ago, Wittenham said:

 

Thank you for the comprehensive reply.  Given that the boat does not have an engine and only gets moved from its permanent mooring site for lifting/blacking, is there a downside to simply taking them off, making the surface smooth and repainting?

Depending on how good or not the internal framing is you might lose a bit of structural rigidly 

[Wittenham]

3 minutes ago, frangar said:

Depending on how good or not the internal framing is you might lose a bit of structural rigidly 

 

It is a butty built by Hancock & Lane in, I think, 1987.  Converted in 2010.  I will try to post pictures of the pre-refurb inside that might shed light on the internal framing.

 

[Mike Tee]

2 hours ago, Wittenham said:

 

 

  Can I assume that problem is localised to the strakes?

 

Assume nothing. So far you have found cost cutting on the build - all I would assume from that is there may well be (possibly many) more probems associated with the hull build. Although if it has lasted since 1987 (and we don't know - not asking - what you paid for it) maybe you've got a bargain. Surprised the surveyor didn't mention tack welded rubbing strakes. Also, if it is a static butty, maybe there is nothing at all to worry about, if it sinks it will be on its home mooring. Hopefully as shallow as the rest of the system.

[Wittenham]

1 hour ago, Mike Tee said:

 if it sinks it will be on its home mooring. Hopefully as shallow as the rest of the system.

It is on Agenda 21 in Oxford.  For all I know it has already sunk and is sitting on the bottom... it would be hard to tell the difference.

[cuthound]

In 1992 I bought a share in my first share boat, built by Pat Buckle.

 

He tack welded the rubbing strakes, but then forced mastic between the strake and the hull. When I sold my share after 10 years they were still rust free.

 

That now ex-shareboat is presently moored at Fradley and the rubbing strakes seem to still be attached and in good condition.

[haggis]

Pat buckle must have got better at attaching rubbing strakes as the ones on copperkins became detached in several.places. 😊

Edited December 14, 2022 by haggis

[matty40s]

This is what happens eventually.

 

 

[beerbeerbeerbeerbeer]

30 minutes ago, cuthound said:

In 1992 I bought a share in my first share boat, built by Pat Buckle.

 

He tack welded the rubbing strakes, but then forced mastic between the strake and the hull. When I sold my share after 10 years they were still rust free.

 

That now ex-shareboat is presently moored at Fradley and the rubbing strakes seem to still be attached and in good condition.

Yes, some of mine are like that, a right old mixture going on. Rivets, welds and mastic.

I replaced some of the mastic earlier this year.

I also had a new rubbing strakes welded top and bottom along both sides, 20’ either side, at a cost of several thousand £’s.

I couldn’t afford to have the bow done, and it would have spoiled the original iron work hence the mastic in places. 

[Feeby100]

6 hours ago, Tony Brooks said:

 

Technically I very much doubt they have been spot welded, but as said they have been tack welded here and there, as have most budget hulls.

 

As rust expands to about 8 times the volume of the steel affected the rust can  build up a considerable force to push the straks off the hull or in the case of windows the frame for the cabin side.

Hi that what I call spot welded my mistake 

[Tony Brooks]

15 minutes ago, Feeby100 said:

Hi that what I call spot welded my mistake 

 

No problem, I fear calling it spot welding may mark a member out as ripe for ripping off.

 

FWIW

 

In this case we are talking about short spaced out runs of weld at the edges of rubbing strip.

 

Spot welding is as found on cars, usually an enormousness clamp like thing uses two electrodes to clamp two pieces of thinish steel together  and applies a currant so you get a little (say 6 to 8mm) rounded indent in the steel ls where the two sheets are fused together. I think rubbing b ands and the steel hull would be too thick with impossible access for typical spot welding.

 

Plug welding might look a bit like spot welding in that it is a series of round welds that may be ground flat, domes or slightly recessed. Typically you may find it when a boat has had the base plate over plated. The new steel with a series of holes drilled in it is pushed up against the old base plate and then an arc mig welder is use to weld through the hols to join the new steel to the old. The weld usually fills the holes right up.

 

 

 

[magnetman]

2 hours ago, haggis said:

Pat buckle must have got better at attaching rubbing strakes as the ones on copperkins became detached in several.places. 😊

 

It was an optional extra to have strakes fully welded. A few hundred extra on the price of the shell. Obviously quite a lot of people buying boats would not understand the relevance and long term importance of this.

 

Similar situation with full length underwater rubbing strakes. Its a very good idea to have a full length underwater rubbing strake but if it costs you a few hundred extra at the build stage a layman who is buying the boat might think it is worth saving the money.

 

 

I have owned two boats by a well known boat builder (Pickwell and Arnold). One of them was built as a shell for a customer and had no underwater full length rubbing strake the other was built for the boatyard as a hire boat and has a full length underwater rubbing strake.

 

Over time the cost of fitting the strake, or the continuous rather than stitch welding of the above water strakes will start to look like rather a sensible investment.

 

Edited December 14, 2022 by magnetman
clarity