Bow Roller Forestay crack - weldable?

[ganter]

Bow Roller Forestay crack with pictures - weldable?

Evening fellow Mariners,

Bow Roller Forestay plate came off today for inspection and lucky it did.

An engineer friend opines that it's weldable but I thought I'd check with my salt water fellows.

Could it be?

Would it be;
a) stronger than before
b) weaker
c) no different.

How about fatigue?

Should I bury it at midnight and get a new one - £230 or so - Ouch.

Many thanks for valuable input.

Ganter

p.s: Boat is Westerly Pageant 23'

 

[crewman]

Re: Bow Roller Forestay crack with pictures - weldable?

I would think it is weldable, but it will need proper preparation, grinding out etc. More importantly you need to find out why it cracked in the first place. Is it up to the job or does it need strengthening?

 

[Tam Lin]

Re: Bow Roller Forestay crack with pictures - weldable?

That looks exactly the same as the one on my Centaur, it even cracked in the same place! I asked around for advice and eventually bought a twin roller one from Trafalgar. In hindsight I wish I had only bought the single roller as the mooring strop is a bit tight on the twin.
I know they are a lot of money but the consequences of failure are disastrous!
Oh yes, although the footprint of my new one was the same the bolt holes were not in exactly the same place, leading to a bit of fettling. Good luck!

 

[savageseadog]

Re: Bow Roller Forestay crack with pictures - weldable?

Welded properly it will be as good as new. Does such an assembly need heat treatment after manufacture?

 

[Lon nan Gruagach]

Re: Bow Roller Forestay crack with pictures - weldable?

Everything can be welded.

Given that someone else has had the same failure I would recommend welding and plating there is an obvious stress point at the outside end of the fracture, possibly due to the heat zone weakness at the end of the existing weld.
The fracture is indicative of upward/ backward stress, I would think this is caused by either ramming something or overzealous parking of the anchor... take it easy.

 

[ganter]

Many thanks for your views chaps.

I have edited the post (pic 1) to indicate where the forestay attaches) to give an indication of stress direction.
To me - the crack is a direct result of forestay over-tension - That'll be down to me and my sailing !!!

Great info so far. Many thanks.

 

[rotrax]

As a practical mechanic with some-albeit old tech-welding expeience I would suggest drilling a hole at the end of the crack, grinding the crack for penatration and having a really good bloke weld it. Argon or tig, not Mig.

Subsequent to welding a triangular plate should be fabricated, the weld fettled, as well as the R/H side where it should be proud of the existing weld in that area and then the plate welded on top, covering the area of the crack and further reinforcing it.

Important to tack it on all sides and then join up to minimise distortion.

My twopenny worth anyway.........................

 

[savageseadog]

Many thanks for your views chaps.

I have edited the post (pic 1) to indicate where the forestay attaches) to give an indication of stress direction.
To me - the crack is a direct result of forestay over-tension...................

Not possible, the mast would or should fail first

 

[Tam Lin]

I think it is a common problem with these boats. I only looked at mine when a friend told me that he had to replace the one on his Centaur. If you look at these boats a fair few have had them replaced and it must be worth Trafalgar's while getting them and selling them.

 

[VicS]

Many thanks for your views chaps.

I have edited the post (pic 1) to indicate where the forestay attaches) to give an indication of stress direction.
To me - the crack is a direct result of forestay over-tension - That'll be down to me and my sailing !!!

Great info so far. Many thanks.

I dont see how forestay over tension would cause that crack.

I'd have thought more likely a bad bit of welding in the first place and/or that it's been smashed on the nose too many times.

Just drilling a small hole at the end of the crack may well stop it progressing any further.

Opinions of Vyv Cox would be useful

 

[30boat]

There's an obvious stress concentration at that point so I'd advise that the crack be ground open and TIG welded and another plate or square bar be welded vertically, joining the plates that hold the roller, to the bar that bolts to the stem. There should be a bit of overlap at the top.
Hope I managed to explain myself...

 

[vyv_cox]

I suspect a quench crack from when the thing was made. Although the crack has initiated at a clear stress concentrator I don't think this is due to forestay tension, the crack has propagated in the wrong direction, i.e. towards the stress. A collision might be more likely. Assuming it to be made from 300 series stainless steel there should be no need for stress relief heat treatment . I have to say it looks like corrosion fatigue, the crack seems to be somewhat intergranular in shape and seems to be stained by chlorides at its surface and presumably internally. Problem is knowing where the stress has come from.

Arresting the crack with a drilled hole, as suggested, is well worth doing. I would have it welded up by someone who knows how to do it properly, then add external strengthening plates.