Cracking - Hull/Deck Joint

[Samosun]

Hi, I'm considering a boat and on inspection found the cracking in the attached images at the bow on what I assume is the Hull/deck joint.

Current owner says it's been there since he's had the boat.

I'd appreciate peoples opinions on this and what it might take to repair (based on the limited info I have given). I have not yet been below deck as with permission I viewed the boat on its mooring without the owner.

I don't mind doing some grp work, but what is the chance this runs further below the wooden trim? is this likely cosmetic or is this a structural issue. Possible repairs needed?

Any constructive input welcome. Thanks!

 

[anoccasionalyachtsman]

Most of the hull/deck joints I've had anything to do with have the 'open edge' at least a couple of inches away from the inside point of the overlap where the joining is actually done. That means that the open edge is really out flopping in the breeze and doing nothing for the strength of the joint. In some circumstances any movement at the open edge is massively amplified compared with the natural flexing of the hull or deck. On some boats (my own included) cracking there is a boring but routine maintenance job, even after forty years.

I'd be looking at the inside to see how the join was accomplished, and if it's (as it looks) the old-fashioned but reasonably reliable layers of grp and I was happy with the thickness and width of overlap, then I'd be tapping it all and hoping to hear a sharp response indicating that it's all nice and solid.

 

[Skipper_Christoph]

This is not the hull deck joint but the hull itself. The crack looks as if it's caused by a major impact. Based on the fact that the crack is on both sides of the hull I would suspect that it is not only cosmetic but further investigation is necessary.

 

[Praxinoscope]

This is not the hull deck joint but the hull itself. The crack looks as if it's caused by a major impact. Based on the fact that the crack is on both sides of the hull I would suspect that it is not only cosmetic but further investigation is necessary.

I would agree with Skipper _Christoph, this looks more like hull damage and unless you are compétent at GRP repairs or are prepared for what may be an expensive repair, I would be walking away from this boat, unless you are being paid to take it away.

 

[pvb]

Hi, I'm considering a boat and on inspection found the cracking in the attached images at the bow on what I assume is the Hull/deck joint.

What is the make/model of the boat?

 

[PaulRainbow]

Without doubt, that is the result of an impact. Would almost certainly have internall damage too and cost a lot to have professionally repaired. You don't give a hint of what the boat is, or its value ? I would want a quote from a competent GRP repairer.

 

[peter gibbs]

GRP will crack superficially along angles where the material has not adapted well to the sudden angularity. This will not translate to the substrate, just be visible as cracks in the gel layer. This will occur very early in the life of the boat and not spread.

That aside, all crack damage to GRP has to be viewed as a result of impact, misuse, or material failure. Of course if the cracking is visible in any way on the underside of the structure, you have your answer. It might not travel further, if stress cracking, but as a purchaser you might want to consider the possibilities. The likelihood of it recurring should you patch and mend is pretty high. But impact cracking, characterised by star cracks radiating, could be repaired with some confidence.

Most of us have some forms of discolouration, mould cracking, and wear erosion - especially on the bow, and bridge deck where many passing hands inflict damage to the GRP. So a used hull of striking perfection is probably not yet on the market, even new.

PWG

 

[anoccasionalyachtsman]

I think we're looking at an unusual biscuit tin hull deck joint, and that the OP knows what he's looking at.

 

[chrishscorp]

I would google for images of the same make and model of boat and have a look at the bow section, do they all have a slight kink in that stainless steel plate ?

 

[Samosun]

Thank you all for your feedback.

For a little more info It's a Macwester 27, mk3 I think. Around £6,000.

Skipper_Christoph - You may be right, I am no expert! However I will add this boat has a very deeply recessed deck with maybe 100mm toe rails (or at least that what I think you'd call them). So the deck itself it 100mm below the upper most GRP you can see in the photos. If that is not the joint then where would it be? You can also see the mould draft on the GRP is opposite in the deck and hull and meets at that crack.

anoccasionalyachtsman - Thanks, regarding your first message :

"That means that the open edge is really out flopping in the breeze and doing nothing for the strength of the joint. In some circumstances any movement at the open edge is massively amplified compared with the natural flexing of the hull or deck. On some boats (my own included) cracking there is a boring but routine maintenance job, even after forty years. "

........That is what I was thinking is a better (maybe not best) case scenario.

Regarding your second message, I never heard of a "biscuit tin hull deck joint " although I can guess you mean the deck sits over the hull profile with an overlapping joint? .....like a biscuit tin What is it you think I know I'm looking at?

chrishscorp - From the images I found this 'kink' does look normal however I have been unable to find good images. It doesn't help that Macwester changed the deck design on these several times. So older boats are completely different.



As I expected opinions are mixed. From "WALK AWAY", to "it's to be expected and probably not a big deal". To be honest I know I need to inspect from the inside and am hoping to do so in the next week. But was interested to get peoples opinions advice before I inspect further. All helpful opinions/info though so thank you!

 

[anoccasionalyachtsman]

Thank you all for your feedback.

For a little more info It's a Macwester 27, mk3 I think. Around £6,000.

Skipper_Christoph - You may be right, I am no expert! However I will add this boat has a very deeply recessed deck with maybe 100mm toe rails (or at least that what I think you'd call them). So the deck itself it 100mm below the upper most GRP you can see in the photos. If that is not the joint then where would it be? You can also see the mould draft on the GRP is opposite in the deck and hull and meets at that crack.

anoccasionalyachtsman - Thanks, regarding your first message :

"That means that the open edge is really out flopping in the breeze and doing nothing for the strength of the joint. In some circumstances any movement at the open edge is massively amplified compared with the natural flexing of the hull or deck. On some boats (my own included) cracking there is a boring but routine maintenance job, even after forty years. "

........That is what I was thinking is a better (maybe not best) case scenario.

Regarding your second message, I never heard of a "biscuit tin hull deck joint " although I can guess you mean the deck sits over the hull profile with an overlapping joint? .....like a biscuit tin What is it you think I know I'm looking at?

chrishscorp - From the images I found this 'kink' does look normal however I have been unable to find good images. It doesn't help that Macwester changed the deck design on these several times. So older boats are completely different.



As I expected opinions are mixed. From "WALK AWAY", to "it's to be expected and probably not a big deal". To be honest I know I need to inspect from the inside and am hoping to do so in the next week. But was interested to get peoples opinions advice before I inspect further. All helpful opinions/info though so thank you!

Yes, a 'normal' hull/deck join is where the hull is moulded with a flange that folds over at more-or-less ninety degrees, and the deck is placed flat on top. Yours has been known as 'biscuit tin' in the trade because it fits down over the outside of a hull with no flange. In the case of your boat, it raised the apparent deck edge to give a bulwark.

I say that it's probably normal flexing, and inspect as you intend.

 

[Samosun]

Thanks anoccasionalyachtsman that makes sense, I had assumed most boats were as you describe, a 'normal' joint.
Going by the shape of this I think you are right about it being an overlapping 'biscuit tin' type joint. I will check carefully.

and I now have a new word "bulwark".

 

[davidej]

I find it hard to believe that any boat was designed with that kind of kink in the SS bow strip. I am definitely in the impact camp here.

 

[Catalina36]

There's no way an impact put that double kink in the stainless steel strip and certainly not right on the joint, it was built that way. An impact would have punched it in in a single curve whereas for it to have a double bend in it, it would have needed something solid on the inside around which to bend it. Anyone who's ever tried to bend SS of that dimension will know how hard that is to do.

That's not to say it hasn't had an impact, merely that it didn't put that kink there.

 

[Buck Turgidson]

these chaps might be able to help: Home Page - Macwester Owners Association

 

[LittleSister]

I can't see a bend on these:

 

[Samosun]

I agree It looks like the crack was probably caused by an impact.....however as Catalina36 says I don't think that it was the impact that bent the metal. The GRP behind it would be completely destroyed by the force needed to create a bend like that. I may not know GRP or boat design that well, but I design heavy stainless fabrications for a living.

Interesting, I agree those boats don't look like they have a kink....however both are difficult to tell. My understanding is many of these boats were owner finished, i'm not sure if that explains a difference. the first one looks like it was maybe filled more heavily as it has a much 'smoother' shape.

 

[pvb]

My understanding is many of these boats were owner finished, i'm not sure if that explains a difference. the first one looks like it was maybe filled more heavily as it has a much 'smoother' shape.

Is it perhaps possible that the boat was supplied as a separate hull and deck, for DIY completion? If that's the case, might the builder have messed up fitting the deck moulding to the hull, making it necessary to modify the stainless steel strap to fit? If that's the case, you'd need to wonder what else wasn't done properly.

 

[bitbaltic]

There are some images of an unfinished Macwester 27 hull here: Unfinished Macwester 27 hull number 2765

Can anything about the hull/deck join be deduced from these? (a bit outside my experience to comment)

 

[Catalina36]

I agree It looks like the crack was probably caused by an impact.....however as Catalina36 says I don't think that it was the impact that bent the metal. The GRP behind it would be completely destroyed by the force needed to create a bend like that. I may not know GRP or boat design that well, but I design heavy stainless fabrications for a living.

Interesting, I agree those boats don't look like they have a kink....however both are difficult to tell. My understanding is many of these boats were owner finished, i'm not sure if that explains a difference. the first one looks like it was maybe filled more heavily as it has a much 'smoother' shape.

I'm glad your professional opinion supports my layman's one. The steel and GRP are in close contact from top to bottom and for the steel to have been pushed back the GRP would have had to go with it, including shortening the deck above. There would have to have been catastrophic smashing and rebuild, in which case why not straighten the steel at the same time? The gelcoat in that area all looks like all the rest and appears original. I tend to agree with pvb's suggestion that it's a bodged home-build in which case the cracking may be no more than cracking of hard filler under stress of the forestay.