What causes these?

[Saltram31]

Looking at a boat to purchase, but has these around the chain plates. Quite a uniform shape.

 

[Refueler]

Looks like backing plate 'work' ... but would need to actually see it first hand.

Need to ask seller - see what he says ...

 

[rogerthebodger]

Yes looks like stress cracks caused by rigid backing plated under the deck.

Further inspection under the deck is necessary

 

[jamie N]

They'll be simply 'marks' from where there'd been a sticky cover over the chain plates to enhance the sealing through the bolt holes. Possibly cut from the shape of the strong back/backing plate.
Edit: That's what it looked like to me at 1st look, which isn't dismissing anyone else's thoughts!

 

[RivalRedwing]

ask your surveyor to investigate

 

[Saltram31]

Thanks. A survey will be done if they accept my offer.

 

[Baddox]

It looks like something has been stuck there then removed. The screws holding the plate on the deck look too small relative to the rigging to hold the rigging forces. So the plate may just be a cover, perhaps replacing a previous bigger one.

 

[William_H]

It is a bit hard to tell from photos.If it is fine cracks in top coat then yes it seems to represent the outline of backing plates under the deck. if that is the case it shows the need for tapered thickness backing plate. Easiest done with multiple layers of grp each layer being smaller in area than the previous layer. So you don't get the harsh transition of load at backing plate edges. I think however that good design would not rely on deck to take chain plate loads but rather transfer loads down in to hull. This may still be practical with this boat if this is the problem. Either by fitting web into corner of hull to deck or bonding plates into hull under chain plates with cable /turnscrews connecting the 2 to take load.

 

[Tranona]

It looks like something has been stuck there then removed. The screws holding the plate on the deck look too small relative to the rigging to hold the rigging forces. So the plate may just be a cover, perhaps replacing a previous bigger one.

Don't think the plate does anything apart from keep the sealant covered. The loads will be taken either by tie rods or to a bulkhead or knee under the deck. There is no way the deck would take the load of all 3 shrouds at one point. There may well be a pad underneath or bonded into the deck and the surface crack in the gel coat is probably the outline of the pad. Unlikely to be structural.

 

[onesea]

Is she a balsa cored deck? Shapes look odd for backing plates. I would like to know what’s below the deck. Put a straight edge on the deck and see if it’s lifted or bowing.
It depends on price age of boat, how rare she is and how much you want her.

 

[fredrussell]

Masking tape ‘peel’ lines after a repair?

 

[Refueler]

If it was not a such a serious consideration for OP - who is considering buying the boat ... I would chuckle at some of the replies ..

Personally - I would have someone experienced in deck / rigging repairs look ... I would like to say Surveyor - but that is a Jack of all and master of none usually. I would be quizzing Seller to explain as much as possible .. if he 'ums and arrs' .... then I would be suspicious..
The marks - are they surface marks or are they actually in the deck material ? Are they cracks or stress pits ?
Does Seller have a recent Survey / Repair history ?
Ask about in the yard where boat is - someone might give up some info ?

Looking at the rigging - I would assume this is not a small budget boat ..

 

[justanothersailboat]

Looks rather regular for stress cracks. Really, really hard to judge from a photo rather than in person. I would base a lot of my feeling on this from how it looks on the underside... if they are uninspectable I'd be quite put off.

 

[fredrussell]

If it was not a such a serious consideration for OP - who is considering buying the boat ... I would chuckle at some of the replies ..

No need to be rude, we’re all just trying to be helpful, but from a distance which makes it difficult.

 

[Refueler]

No need to be rude, we’re all just trying to be helpful, but from a distance which makes it difficult.

Not being rude at all ... just plain speaking ... if we at a pub - it would be just taken as a comment and all smile.

But that's the problem ... we only have the photos to go by .. and why I say - it needs someone to seriously look .. and TBH - many Yacht Surveyors are not quite up to it !!

 

[Refueler]

Looks rather regular for stress cracks. Really, really hard to judge from a photo rather than in person. I would base a lot of my feeling on this from how it looks on the underside... if they are uninspectable I'd be quite put off.

That's my thought as well ... stress would normally have cracks / lines radiating out ... not uniform lines ...

First thought was maybe deck had been cut - work done - then glassed back .. BUT without actually seeing it first hand ???

 

[RivalRedwing]

If there is an owners association out there they may be able to provide specific knowledge

 

[Graham376]

Is it a Moody? Many, including ours, have an identical square score mark around the deck chain plates. Appears to be some idiot at the factory was cutting off some sort of deck protector, with a Stanley knife.

 

[doug748]

It looks like something has been stuck there then removed. The screws holding the plate on the deck look too small relative to the rigging to hold the rigging forces. So the plate may just be a cover, perhaps replacing a previous bigger one.

I agree with that. Those marks look like a line of adhesive / sealant, though it is difficult to imagine how they got to be so fine. If Saltram gets an ink rubber and has a go, a magnifying glass may reveal they have vanished.

Failing that, Graham's idea looks good. Either way, I would not be losing faith in the boat just yet.

.

 

[Buck Turgidson]

Never in the history of stress crack have they followed such a perfect outline of anything. They are definitely man made.