thinwater
Well-Known Member
Yes, I should have said tension.
No, the tension (torque plus rigging) are not additive. Balanced, but not additive.
How tight to torque my chainplates
- Thread starter iamtjc
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No, the tension (torque plus rigging) are not additive. Balanced, but not additive.
Refueler
Well-Known Member
As a young lad spending many hours in yacht builders and later as a Surveyor - I NEVER saw a Torque wrench used on such fittings ... in fact apart from engine related - I cannot recall any use of a torque wrench on a boat.
ducked
Well-Known Member
Moodysailor
Well-Known Member
There's some over-thinking on this thread... 
Tight is the answer - as you have a solid epoxy core, tighten it up until firm. Do not leave slack on any fastener that is subject to high loads or cyclical loads. If you need a torque setting as you don't trust your arm, 50Nm for stainless steel. As you can only fit one nut, use a lock nut (nylock). Make sure you have a good backing plate.
Tight is the answer - as you have a solid epoxy core, tighten it up until firm. Do not leave slack on any fastener that is subject to high loads or cyclical loads. If you need a torque setting as you don't trust your arm, 50Nm for stainless steel. As you can only fit one nut, use a lock nut (nylock). Make sure you have a good backing plate.
thinwater
Well-Known Member
2) How much to torque the bolts. It's my rigging so I want them tight but I don't want to crush the deck. The U-bolts are 10mm 316 stainless.
3) How to ensure they don't come undone if the butyl oozes more in hot weather and relieves the tension in the bolt. There isn't room between the bottom of the deck and the headlining for a second nut or similar.
The OP asked for a torque value. No one gave a quantitative basis or reasoning for one. That is what I did. No one mentioned that the toque before and after tensioning the rig are very different. At the very least, the tension should be rechecked, with sealant pushing out, when the rig is fully tensioned. That is still only ~ 40% of the sailing load, but it's a start.
As for not loosening, the OP can use Locktite or an elastic locknut. Also, conventional jam nuts to prevent loosening are only 1/2-thickness and would probably fit. In fact, loosening is only really a factor if the bolt is under-torqued and cycling between tensioned and loose.
3) How to ensure they don't come undone if the butyl oozes more in hot weather and relieves the tension in the bolt. There isn't room between the bottom of the deck and the headlining for a second nut or similar.
The OP asked for a torque value. No one gave a quantitative basis or reasoning for one. That is what I did. No one mentioned that the toque before and after tensioning the rig are very different. At the very least, the tension should be rechecked, with sealant pushing out, when the rig is fully tensioned. That is still only ~ 40% of the sailing load, but it's a start.
As for not loosening, the OP can use Locktite or an elastic locknut. Also, conventional jam nuts to prevent loosening are only 1/2-thickness and would probably fit. In fact, loosening is only really a factor if the bolt is under-torqued and cycling between tensioned and loose.
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Rhylsailer99
Well-Known Member
What is the best then butyl or sikaflex? I did some with butyl and a the main rear and side shrouds with sikaflex. I suppose if they start leaking with butyl it would be easier to loosen and re apply.
thinwater
Well-Known Member
I think the important thing is that they do not move. Either will be fine.
I'm a big fan of butyl for hatches most things that are through-bolted. If attached only by screws, the bonding qualities of the sealant may be an important part of the connection. Check plastics before using butyl; many are subject to crazing and cracking, including acrylic glazing.
Refueler
Well-Known Member
Personally - for fittings that are 'permanent' ... I prefer to use external grade PU glue ... why ?
1. Its Seawater prrof.
2. As it sets - it expands and seals
3. It adds to the bonding of fitting
4. Its actually not a big problem if you need to remove fitting later - unlike Epoxy or other Hard resins.
My pulpit on the 25ft had to be repaired after it was hit and one side bent. Local Fishing Harbour workshop sorted the bend ... and I then refitted the pulpit with PU glue applied .... bolted down all flush - which squeezed out excess PU glue ... Once set - I ran a sharp knife round and removed the excess.
I used Bison PU External Grade PU :
I use it for many jobs due to its Gap Filling properties ....
I know someone will pop up and say - but it doesn't have same 'spongy' factor as butyl etc .... if the fitting is made well and bolts / screws tight - there will be no problem ... it works.
1. Its Seawater prrof.
2. As it sets - it expands and seals
3. It adds to the bonding of fitting
4. Its actually not a big problem if you need to remove fitting later - unlike Epoxy or other Hard resins.
My pulpit on the 25ft had to be repaired after it was hit and one side bent. Local Fishing Harbour workshop sorted the bend ... and I then refitted the pulpit with PU glue applied .... bolted down all flush - which squeezed out excess PU glue ... Once set - I ran a sharp knife round and removed the excess.
I used Bison PU External Grade PU :
I use it for many jobs due to its Gap Filling properties ....
I know someone will pop up and say - but it doesn't have same 'spongy' factor as butyl etc .... if the fitting is made well and bolts / screws tight - there will be no problem ... it works.