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  #1  
Old 02-23-2005, 02:32 PM
Jack D Davis Jack D Davis is offline
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Removing silicon caulking on aluminum

I purchased just yesterday an old ('68) 12' Starcraft in riveted aluminum and it is very restorable (few dings, and tight). It badly needs paint, yet the previous owner used silicon caulking to seal the riveted joints. Since paint won't adhere to silicon sealers, I need to remove it........any suggestions?

This will be a temporary boat. Plans are to build a welded aluminum boat this coming Winter after I finish a house project. Still, I think I should restore it to it's previous glory
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  #2  
Old 02-23-2005, 02:48 PM
cyclops cyclops is offline
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Do it right. Call GE or Dow Corning.
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Old 02-23-2005, 04:05 PM
D'ARTOIS D'ARTOIS is offline
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Use MEK......but don't inhale it!
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Old 02-23-2005, 05:22 PM
cyclops cyclops is offline
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35 years of heat and cool have probably loosened the rivets a little. A light tap on the head and another person on the other side with a support block. Like new. Or the aluminum may be going soft due to aging. Does happen.
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Old 03-03-2005, 03:21 PM
Dr. J Dr. J is offline
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Are you sure that the compound is silicone and not a bedding compound? Silicones are used primarily as caulking around windows and the like, while bedding compounds such as 3m and sikaflex can be used in underwater applications. If the goop can be rolled off with simple finger pressure then it is probably silicone. If it is very difficult to pull off, then it is probably bedding compound.Although I have not used the product myself, a shipwright friend of mine has used Debond 2000 with great success. Ensure that you degrease and prep the surface for painting once you have removed the compound. A word of caution. If the previous owner had applied compound over the rivetting, then I would ensure that they are in good shape prior to painting. You might have to address corroded or damaged rivets before considering painting.
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Old 03-03-2005, 03:32 PM
Thunderhead19 Thunderhead19 is offline
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Personally, I have found that riveted boats wear out. Then you have to throw them away. Rivets are a special kind of fastener in that they can't withstand shear forces. They work by clamping the metal together so hard that the friction between the plates prevents slipping and prevents the rivets from shearing off. Once the rivets start to come loose, unless you replace all the rivets with new ones, there is no strength left in the hull at all. Maybe you can tighten them up for a while but eventually they will just break. What happens then? all the caulking in the world won't hold the sides and bottom together on your boat. You could use structural adhesive instead. Autobody type structural adhesives are as strong as a weld in many applications. You'll probably wind up spending $60-$80 on a tube of the stuff, and it will probably do your whole boat. I don't think it's worth it, but hey, as long as you're having fun. Righ?
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Old 03-07-2005, 02:08 AM
Jack D Davis Jack D Davis is offline
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Thanks for the suggestions. Yes. Dr. J. it is silicon caulk like used on homes. Too bad it wasn't the paintable type, but it isn't. It will have to be removed. I would expect a riveted boat to leak some. It seems tight and holds rain water very well. Why they put that stuff on it is a mystery. There is a small damaged area that will need to be repaired. It is well above the water line, so I will probably just fill it before painting.

I'm wanting to build a welded aluminum fishing boat so bad I can taste it and if my plan goes right, I'll start it this coming Winter. I used to have a plywood pram back in the 60's and I loved it....except it was way too small. The biggest plan I can find for a pram is 10'...still too small. If anyone knows of a plan for a 12'-13' pram design, either shallow "V" or flat bottom, I'd sure like to hear about it. Especially if it's for welded aluminum construction.
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Old 03-07-2005, 05:44 PM
Thunderhead19 Thunderhead19 is offline
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I think it stops being a pram after about 10'. You want something like a Jon Boat or even a Dory?
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Old 03-07-2005, 08:33 PM
Jack D Davis Jack D Davis is offline
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Ken Hankinson has three that appeal to me. Only one is for aluminum and it is too large (Scrambler). Another is the Headwater Transport, (10' Pram) stitch and glue and too small. The last is about the right size for my 8HP motor and will suit my purposes, but is for plywood construction.......I'm wondering if a plywood plan can be converted to welded aluminum without a lot of trouble.

http://www.boatdesigns.com/cgi-bin/s...=3057172_26879
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  #10  
Old 03-07-2005, 11:42 PM
Dr. J Dr. J is offline
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Jack, Most flat bottom skiffs can be built in no time at all due to the simple shape and lack of any hard or compound curves. You would not require many station lines in order to develop the plating, and fitting would go fairly quickly. If you have access to information regarding the Canadian fishing industry, I would suggest researching the old commercial fishing industry or visit a maritime museum to check out the dead skiffs that were used during the seining fisheries. These "dead"skiffs were simple ,yet very capable row boats that could take a good pounding and also be beached in rather incliment weather. Generally the guy rowing them could even stand up and use 10-12' oars ! Their basic design is not unlike the ones that you have mentioned in your posting. You can still find both the wood and aluminum built dead skiffs in some of the local yards here in the Pacific southwest. If you can't purchase one,you could at least see for yourself what their design is like.
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