U bolts and V bolts

[iamtjc]

My surveyor recommended I replace the shroud U bolts when I replace the the standing rigging on my Hunter Horizon 272.
The existing bolts are more of a V shape. Fortunately they are angled on the deck so no problem with finding cranked fittings.
I haven't been able to find a supplier of V bolts (I'm happy to have suggestions). I can't see that using U bolts would make a lot of difference but thought I would check the received wisdom of the forum.

 

[[194224]]

Are these any use for your particular application? Various sizes bearing the name "seasure" as yours do but, although it's hard to gauge, I suspect yours a larger than the ones they have available.

316 Stainless Steel V Bolts

 

[iamtjc]

Thanks. You are right though, these would be too small.
I measured mine at 9.55mm thick on 51mm centres, so I guess they are nominally 10mm on 50mm centres.

 

[wallacebob]

Are you a Hunter Assoc member? I'd ask the question there, as there are some very knowledgeable persons around that forum. H27 are very pop.

 

[ylop]

Thanks. You are right though, these would be too small.
I measured mine at 9.55mm thick on 51mm centres, so I guess they are nominally 10mm on 50mm centres.

3/8" by 2" surely?

 

[Martin_J]

There's a parallel thread about angled v bolts...

Cranked V-Bolts

It seems to have come up with an answer but the same supplier has straight M8 and M10 v bolts.

Stainless Steel Triangle Padeye / straight / M8 x 50 mm only 21,95 € | SVB

 

[PCUK]

Trouble is, surveyors have to find something to suggest, especially if the boat is good!

 

[iamtjc]

3/8" by 2" surely?

Yes that makes sense. I keep forgetting the boat is essentially imperial.

@Martin_J Thanks, I saw that thread, however the Bluewave M10 V bolt is on 60mm centres and that won't fit with the underdeck fitting on my boat that transfers the load to the bulkhead.

So the big question remains.... Is there any good reason not to use a U bolt.

 

[andsarkit]

Southern Rigging Supplies I found these after a long search when I needed some for my 50 year old boat.

 

[B27]

Also known as 'hairpin chainplate'?

Don't these have a bit of a bad reputation?
I'd be concerned about the welded on plate, fatigue and all that.

 

[Martin_J]

Although as the original poster asks.... Is it really preferable to have a V shaped bolt if the pull is not directly upwards.

One does wonder if the vertical pull is angled towards the mast, does an inverted U shape bolt better spread the load between it's legs (when compared with an inverted V that might put more stress on the outboard side leg).



I don't want to add another question but should they be angled v bolts at about ninety degrees to how they're located now.

 

[andsarkit]

Displacement of the yacht is 2218kg and the breaking load of the A bolts I linked is 5100kg. I don't think strength is an issue if there is a slight angular misalignment as the 5mm (?) rigging wire has a break load of 2000kg and would break first.
I agree with Martin_J that from an engineering point of view it is better to align the loading but many yachts are fine with a slightly imperfect arrangement as there is plenty of redundancy.

 

[Neeves]

Displacement of the yacht is 2218kg and the breaking load of the A bolts I linked is 5100kg. I don't think strength is an issue if there is a slight angular misalignment as the 5mm (?) rigging wire has a break load of 2000kg and would break first.
I agree with Martin_J that from an engineering point of view it is better to align the loading but many yachts are fine with a slightly imperfect arrangement as there is plenty of redundancy.

There is plenty of redundancy defined by your post but it is the deck taking the load - much depends on the size of the backing plate under the deck and any reinforcement designed into the deck for the historic bolts.

Our cat had reinforced pads in the hull for the stays for the bowsprit but for some reason the pad eyes were located in an unreinforced area. I added sections of glass and large, 150mm square x 6mm backing plates. Whether it was necessary - I don't know - I'm just cautious - and it was an easy fix.

Is your deck strong enough to take misalignment and if you don't know - can you add bigger backing plates?

Jonathan

 

[Rhylsailer99]

There's a parallel thread about angled v bolts...

Cranked V-Bolts

It seems to have come up with an answer but the same supplier has straight M8 and M10 v bolts.

Stainless Steel Triangle Padeye / straight / M8 x 50 mm only 21,95 € | SVB

View attachment 161259

These are the best quality ones and the ones i fitted for my cobra 850 shrouds. I upped the size to 10mm as they matched the centre size once I re drilled the holes.


Blue Wave Stainless Steel A-Bolt - Angled & Straight - 6 Sizes these are the ones you want to use they're the best quality available I found.

I also used big oversize stainless bars underneath the plywood for more support and strength.

 

[iamtjc]

Thank you @andsarkit and @Rhylsailer99. That's 2 possible sources of exactly what I need.

Ref, your question @Neeves. Here are pictures of what is under the deck. The backing plate isn't that big but has rod connecting it to the bulkhead.
To be honest I don't know how strong that weld at the top of the rod would be but the boat has done 33years with this arrangement.
There is some corrosion in the picture, I think it is probably from someone using a mild steel washer instead of stainless, but more reason to change them anyway.


Rod connection to the bulkhead.

 

[Neeves]

It looks as if the original arrangement is sufficiently beefy - the rod looks well oversized. You will obviously check the weld before you add the new 'V' bolts.

Jonathan

 

[Rhylsailer99]

Thank you @andsarkit and @Rhylsailer99. That's 2 possible sources of exactly what I need.

Ref, your question @Neeves. Here are pictures of what is under the deck. The backing plate isn't that big but has rod connecting it to the bulkhead.
To be honest I don't know how strong that weld at the top of the rod would be but the boat has done 33years with this arrangement.
There is some corrosion in the picture, I think it is probably from someone using a mild steel washer instead of stainless, but more reason to change them anyway.
View attachment 161320

Rod connection to the bulkhead.

View attachment 161321

I have one spare that I bought extra by mistake I think its 8deg angle 10mm bluewave

 

[Rhylsailer99]

My surveyor recommended I replace the shroud U bolts when I replace the the standing rigging on my Hunter Horizon 272.
The existing bolts are more of a V shape. Fortunately they are angled on the deck so no problem with finding cranked fittings.
I haven't been able to find a supplier of V bolts (I'm happy to have suggestions). I can't see that using U bolts would make a lot of difference but thought I would check the received wisdom of the forum.

View attachment 161257

pics of the two I have spare. The better quality one is the bluewave as you can see in the pics.

 

[Rhylsailer99]

3/8" by 2" surely?

bluewave 10mm A bolts are 50mm centre so if you over drill the holes to 10.5mm I'm sure they would fit.