My 1982 H27 uses the typical U-bolts many of us have. My question is, what is the best way to check there condition. They look fine, but looks can be deceiving. I know that chainplates should be inspected regularly, even dye tested, has anyone dye tested the u-bolts?
inspecting Chainplates/Ubolts
- Thread starter Mike 1
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Earlier in the spring all the chain plates and U-Bolts were replaced on my boat. You are right U-Bolts are hard to evaluate. The experienced rigger I had do the rigging work said that U-Bolts are stressed by their nature - taking a bolt and bending it into the U shape. After 30 years of use, the U-Bolts should be replaced with new ones. The cost is not prohibitive and they are fairly easy to change out. I did mine with little trouble. I had a hard time lifting the old U-Bolts off. It took a large lever and a fair amount of force to do it. The Cherubini chain plates and U-Bolts are easy to access. I replaced them all with the help of some friends. Document where each chain plate and backing plate come from so that when you replace them you can match the new chain plates with the backing plates and locations. Hunter did not drill all chain plate holes uniformly and replacements must go to the original location and be backed with the original backing plate.
Mike, have they ever been replaced? Your 1982 is really beyond the safe limit for SS bolts susceptible, because of where they are and how they are mounted, to crevice-crack corrosion failure. We discovered this on Cherubini 44s, went through mad gyrations trying to come up with something better, and for the most recent boat returned to $12.99 316-stainless U-bolts from Attwood. They are for cheap ski boats! -- and we use them to hold up the rig. And the worst downside is that we have to recommend that they be changed every 12-15 years. That's a no-brainer.
I have lately removed some bolts from my toerail, most recently to install U-bolts at the back end for the backstay legs. I found with just a little 'persuasion' the bolts back right out of the rail with a hammer. For your boat I would not hesitate to hammer out all the U-bolts, get new ones, and install them with a little flood of 5200 under the outer washers. Don't buy junk from China. I would avoid Suncor (have had awful experiences with lousy castings and machining quality). Look in Defender and elsewhere and buy good ones. Some of them might be metric-- get the correct 316-SS locking nuts for them.
These parts are both too cheap and too crucial not to consider this a 'duhh'. The whole boat's worth won't cost $150.00. Do it this season and the boat will last till the next owner retires.
I have lately removed some bolts from my toerail, most recently to install U-bolts at the back end for the backstay legs. I found with just a little 'persuasion' the bolts back right out of the rail with a hammer. For your boat I would not hesitate to hammer out all the U-bolts, get new ones, and install them with a little flood of 5200 under the outer washers. Don't buy junk from China. I would avoid Suncor (have had awful experiences with lousy castings and machining quality). Look in Defender and elsewhere and buy good ones. Some of them might be metric-- get the correct 316-SS locking nuts for them.
These parts are both too cheap and too crucial not to consider this a 'duhh'. The whole boat's worth won't cost $150.00. Do it this season and the boat will last till the next owner retires.
Are these the u-bolts you are referring to? If so, I better do the change out. I presume that this can be done with the mast still up? I could utilize my topping lift which is SS wire affixed to the mast head as a temporary back stay when the u-bolts are changed out.
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You could use a halyard or two in addition to the topping lift. And you will back off several turns on the shrouds naturally. Forestay too if possible. I know some don't adjust after the furler is installed. But mine does.
Rardi, yes those are the U-Bolts. I purchased mine from Marine Max. They are a power boat store but I find a lot of good prices there. There seems to be one in Emeryville out where you live. When taking the Bimini off, doing one side of the split back-stay at a time keeps the mast up. Of course another line, even the main halyard tied to the stern gives you peace of mind.
I was looking at various u-bolts, is there a safe load rating I should be looking for? The last thing I want it to replace these and put the wrong ones in. something like this in the correct size?
http://www.defender.com/product.jsp?path=-1|118|311635|312082&id=125319
http://www.defender.com/product.jsp?path=-1|118|311635|312082&id=125319
Assuming the right size those Wichards would be fine. Here is a load chart for those over on PYacht: http://www.pyacht.com/wichard-u-bolts.htm . The 13/32"(10 mm) seems to be the largest and rated at 4500 kg or almost 10,000 lbs.
Mike, don't buy just anything. U-bolts from reputable people will give load ratings. They are typically WAY overkill for what you need; but it's nice to have the info.
Once we were rolling a Cherubini 44 out of the shop at about 4.15 one afternoon when the dollies broke and the boat plunged straight down, cutting the plywood cradle gussets in shear, to come to rest at a sickening angle in the middle of the shop with 15 minutes to go till the end of the day. The worry was for how to stabilize it there till tomorrow. I remembered the Attwood 1/2" U-bolts we were using as main chainplates, set through the deck with a 7'-long piece of 2" SS angle for a backing plate under the magnificently-robust fiberglass sheer clamp, were rated at 16,000 each. I said two of them would lift the boat of you could balance it; four (using the mizzen's 3/8" ones at 12,000 each) could actually be used as lifting points for a 29,000-lb boat. We took a few lines from the U-bolts to structural members of the building itself and went home, solving the problem the next day.
Read my post. I would use the Attwood or Sea Dog ones because they give safe working loads. Remember that, used with clevis pins that are much too small for the inner radius of the U-bolts, the U-bolts under load will attempt to distort to match. They will 'egg' towards a tighter V at the top. This is expected. Simply tighten the rigging every so often-- not a lot, just to maintain tension. Once 316 stainless moves once, on a molecular level, it will take 10 times that load to move it again. The metal gets about that much more brittle, so keeping the rigging snug is vital to avoiding shock loads-- but in practice this would only be a danger if the rig were really very loose, ill-maintained for a long while, and in very severe conditions. You'd see the mast whipping about at the top before the bolts failed.
And do replace them every 12-15 years; and inspect them with a cautious eye every season at least. If they ever look brown, there is less moly or nickel than there should be and they are rusting; so replace them then.
Mike, Ed, the ones you showed us are more money than they have to be. Also the Wichard ones are metric; and I don't like the rubber boot because it is solid and does now allow you to get the 5200 right into the tops of the bolt holes to stop leaks. I prefer to take that thing right off and use locknuts against bright SS fender washers as trim rings on the deck. Looks better too.
Once we were rolling a Cherubini 44 out of the shop at about 4.15 one afternoon when the dollies broke and the boat plunged straight down, cutting the plywood cradle gussets in shear, to come to rest at a sickening angle in the middle of the shop with 15 minutes to go till the end of the day. The worry was for how to stabilize it there till tomorrow. I remembered the Attwood 1/2" U-bolts we were using as main chainplates, set through the deck with a 7'-long piece of 2" SS angle for a backing plate under the magnificently-robust fiberglass sheer clamp, were rated at 16,000 each. I said two of them would lift the boat of you could balance it; four (using the mizzen's 3/8" ones at 12,000 each) could actually be used as lifting points for a 29,000-lb boat. We took a few lines from the U-bolts to structural members of the building itself and went home, solving the problem the next day.
Read my post. I would use the Attwood or Sea Dog ones because they give safe working loads. Remember that, used with clevis pins that are much too small for the inner radius of the U-bolts, the U-bolts under load will attempt to distort to match. They will 'egg' towards a tighter V at the top. This is expected. Simply tighten the rigging every so often-- not a lot, just to maintain tension. Once 316 stainless moves once, on a molecular level, it will take 10 times that load to move it again. The metal gets about that much more brittle, so keeping the rigging snug is vital to avoiding shock loads-- but in practice this would only be a danger if the rig were really very loose, ill-maintained for a long while, and in very severe conditions. You'd see the mast whipping about at the top before the bolts failed.
And do replace them every 12-15 years; and inspect them with a cautious eye every season at least. If they ever look brown, there is less moly or nickel than there should be and they are rusting; so replace them then.
Mike, Ed, the ones you showed us are more money than they have to be. Also the Wichard ones are metric; and I don't like the rubber boot because it is solid and does now allow you to get the 5200 right into the tops of the bolt holes to stop leaks. I prefer to take that thing right off and use locknuts against bright SS fender washers as trim rings on the deck. Looks better too.
Even these Navtec, high quality, rigging specific, forged/machined u-bolts can fail. Navtech no longer sells these and they were rated for more than anything off the shelf you can buy today in that OD. While they were "technically" over engineered for the boat it does not give one a warm and fuzzy feeling to use new u-bolts rated at less than the originals that failed in 20 years. 
What ever you do BUY QUALITY and ask for the country of origin.
What ever you do BUY QUALITY and ask for the country of origin.
I finally found decent u-bolts from Sea Dog Line hardware. These are decent, 316-stainless parts from Taiwan (ROC, not PRO China). The 8-mm ones are perfect for my boat (almost 5/16"). As Sea Dog is sold only to distributors you have to find someone who stocks some of their stuff and order them if they're not on-hand. But they're nice parts.
So long as they go through the aluminum toerail the backing plates don't have to be anything stupendous. My boat currently has a plate of stainless about 22" long and 1" wide; drilled out for 2-leg u-bolts this will be adequate with the addition of 316-SS fender washers. That toerail can be a godsend to those of us with 1970s boats. One blessing of this boat of which I have restored about 85% is that the toerail doesn't leak.
So long as they go through the aluminum toerail the backing plates don't have to be anything stupendous. My boat currently has a plate of stainless about 22" long and 1" wide; drilled out for 2-leg u-bolts this will be adequate with the addition of 316-SS fender washers. That toerail can be a godsend to those of us with 1970s boats. One blessing of this boat of which I have restored about 85% is that the toerail doesn't leak.
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