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08-03-2013, 04:20 AM
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#1
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Admiral
Join Date: Jan 2005
Home Port: Darwin
Vessel Name: Sandettie
Posts: 1,917
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Bedding-in deck hardware.
I had a beer last night with a couple of highly experienced sailing boat owners. Talk of maintenance led me to relate a story of my sheet lead tracks. They are bronze, gunwale mounted and secured with 6" stainless steel bolts.
When I recently replaced these bolts, which I discovered were seriously corroded at the point where they go through the deck, I pointed out the difficulty I had in tightening them down, and my desire to do so before the sealing compound had set.
One sailor said I should only 'finger' tighten the nuts until the compound is set, one agreed with me in part, saying he waits until the compound has started to 'go off', then there is me. I have always tightened the nuts holding down deck hardware until they are tight whilst the bedding compound is still soft. A couple of days later, I will go back and give each nut a further half turn.
Of course the underlying reason for tightening the bolts and using bedding compound is to solidly secure an item and to prevent leaks. I wonder if there is a benefit in not tightening nuts until the compound has fully set.
Either way, I learned that it is necessary to clean new stainless hardware with a solvent before bedding it down. Apparently the wax residue left after polishing in the factory, acts as a release agent and may prevent full and lasting adhesion of the compound to the hardware.
For the record I have always used Sika sealing compounds and the only failure I was ever aware of was followed the bedding down of new stanchions on a 36' ketch I put together in the early 80s.
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" if at first you don't succeed....Redefine success"!
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08-03-2013, 07:56 AM
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#2
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Moderator
Join Date: Jun 2007
Home Port: Washington DC
Vessel Name: SV Mahdee
Posts: 3,236
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Hey Auzzee--thanks for the info. The really important thing to remember is that if you tighten it down too much, the sealant will be squeezed out and it is possible you won't have a sufficiently thick layer of bedding material to keep the seal. The thicker the layer of bedding, the more movement it can handle w/o breaking away from the deck or whatever is being bedded to the deck.
The best materials will have a low modulus of elasticity so that the bedding can be compressed or will stretch to bridge the required movement/gap. Sailor's favorite "do everything googe" of 3M 5200 is not a low modulus material and while it's a great adhesive, it is doomed as a sealant for things that will have flexing/movement. Sika Flex is owned by (or owns) the Tremco company. As an aside, a lower cost way of getting the same performance/material is to purchase one of the Tremco silicon modified polyurethane sealants that is sold for the construction industry. There are dealers who carry both brand names and have a cross-reference to which-is-what
On tightening things down--we make a decision about how thick the bedding should be to achieve a successful long-lasting seal and tighten down the fasteners until we've achieved that thickness. Sometimes it's finger tight--sometimes it's just about all the way to where it needs to be. Then, we wait 24 hours and then we tighten up the fastener(s).
We tape off the item being bedded and we tape the deck around the item so that it is simpler to have a nice, neat job.
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08-04-2013, 01:42 AM
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#3
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Commander
Join Date: Sep 2004
Home Port: Darwin
Vessel Name: Gone Troppo
Posts: 103
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Hi David, I find Butyl Rubber Tape much better and easier to use for sealing deck fittings. It is not a glue so its use is restricted to only where we use mechanical fastenings. I used this on our Targa Bar back in 1998 and it is still performing perfectly. It also makes it much easier to remove hardware.  Great for hatches and cleats!
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08-04-2013, 09:50 PM
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#4
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Lieutenant
Join Date: Jun 2013
Home Port: Stockholm
Posts: 92
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Re Redbopeeps' pic of blue tape surounding an airvent. Looks like the same airvent I'm replacing on my Storfidra. Haven't bedded yet, so this post came just in time for me  A neat trick too is how R. wrapped tape around the tip on the Sika Flex tube. Equally glad to learn Stephen's butyl tape method and Auzzee's tightening info. Hearty, thx guys//Joe
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08-06-2013, 12:55 AM
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#5
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Commander
Join Date: Sep 2004
Home Port: Darwin
Vessel Name: Gone Troppo
Posts: 103
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08-06-2013, 04:26 AM
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#6
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Moderator
Join Date: Jun 2007
Home Port: Washington DC
Vessel Name: SV Mahdee
Posts: 3,236
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Butyl Tape Ah that's another good thing. It's the stuff that you'll find in the constuction industry for roof/door/window flashing. Sticky backed thick stuff they have there. We used roofer's Butyl tape on the wood structure supporting our fuel tanks. Butyl tape went down on the frames, plain rubber stuck to it (doesn't absorb water) and then the fuel tanks sat on top of that.
We still have the better part of a roll of that 4" wide Butyl Tape. I''ll have to find a use for it.
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08-06-2013, 05:09 AM
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#7
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Admiral
Join Date: Jan 2005
Home Port: Darwin
Vessel Name: Sandettie
Posts: 1,917
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Thanks heaps Stephen. The article with photos for which you published the link Bedding Deck Hardware With Bed-It Butyl Tape - SailboatOwners.com is probably the best advice I have ever read on the topic of bedding deck components.
It is a quite long article, but I commend it fully to anyone who had a similar question as I had regarding sealing deck hardware. For sure, I will adopt the use of Butyl and will tighten once.
Again Stephen, thank you sincerely for bringing my attention to this article.
Cheers
Dave.
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" if at first you don't succeed....Redefine success"!
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08-07-2013, 12:51 AM
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#8
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Lieutenant
Join Date: Jun 2013
Home Port: Stockholm
Posts: 92
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Kudos to Stephen re links on bedding w/outstanding pics and text much obliged//Joe
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08-09-2013, 04:29 PM
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#9
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Admiral
Join Date: Jan 2007
Vessel Name: Persevate
Posts: 548
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That is indeed a great article.
I never thought of countersinking but have always potted any wholes with CPES before rebedding hardware, to give a waterproof barrier between deck core and potential leaks, and to reinforce any potential unseen soft spot... Think I'll add the countersink to all future installations as well.
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08-25-2013, 02:03 AM
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#10
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Lieutenant
Join Date: Feb 2010
Home Port: the boat
Vessel Name: Skipping Stone
Posts: 79
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On this one I am definitely "old school".
I prefer bedding compound, the real stuff (Bedlast is one trade name), made from linseed oil and other stuff. It never hardens and should last 15 to 20 years. It shouldn't matter if you tightened it progressively or immediately as it remains flexible.
However as I believe you have a steel boat, it is most important that you insulate the bronze from the steel, as I'm sure you are aware. I believe the Bedlast is a better insulator than most of the more modern products.
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