fasteners and waterproofing..

Greetings all,

I'm a first time boat builder and tend to read myself stupid before I begin any endeavor.  Having just begun construction on a 14' driftboat, there is one question (of many, I'm sure..) that I have yet to find an answer for:

When you are building your boat, inevitably you would get to a point where it would make more sense to finish the hull BEFORE building out the interior and/or finishing the exterior.  My question therefore is, how to you properly seal fasteners and the holes they make that have been put in AFTER the glass and epoxy?  

Example : upper and lower rub rails.   It stands to reason that they aren't glassed with the hull, so when you drive that screw through to the frame, what's keeping that water from wicking into the hole you just made?

Thanks!

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Permalink Reply by Rick Newman on February 6, 2012 at 9:12am

Micheal, I am not sure exactly what parts you are referring to. However i am presuming you mean the outer gunwale (at the top) and the outer chine at the juncture of the side and bottom panels. There are numerous sticky sealants/adhesives that have been used. 3M 5200 or 4200 being representative of these substances. Boat Life, is similar but different, I believe it is a polysulfide base. The concept is similar, no matter which of these you choose, the wood needs to be protected from water intrusion.

Jamestown Distributors is just one of many suppliers that offers a wide selection of sealant/adhesives. Some are exceedingly strong and often the woods adheared by 5200 will fail before the the 5200 does. Since some of the parts of a driftboat, especially inner and outer chines maybe damaged during use it is handy to be able to dissassemble these parts to allow their repair. So a juncture that is too strong can make this difficult.

Initial installation of 5200 can provide you with hours of enjoyment removing it from your skin, tools and undesired surfaces. Other products are not as "sticky" and can be more easily removed and may be easier to separate if repairs are required.

The search function on this site will provide you with a couple of hours of reading concerning the potential choices, installation techniques and advantages and disadvantages of the potential products.

I hope that I interpreted your question appropriately and provided a start for further discussion on this controversial subject.

Rick Newman

Permalink Reply by Michael Rosso on February 6, 2012 at 9:44am

Thanks a ton, Rick.   I'll start researching tonight!  I didn't have much luck when I searched the site, but I'll try again using the terms you mentioned.

I completely agree that these particular items should be fairly simple to remove/replace without having to damage your boat.   My original question also applies to seat brackets, decking, etc.   The more I think about it, the more confused I become, and the more I begin to think that there most likely ISN'T a fool proof way of sealing such things where they attach to the hull.   Someone please tell me I'm wrong. :)

Permalink Reply by Rick Newman on February 6, 2012 at 10:50am

I had tried to add some photos of plugging holes with bungs but the site timed out before I got done. Anyway, any screws placed can have some of whatever sealant you are choosing applied to them as you insert them. A bung or plug can be inserted into a hole above the top of the screw. A stepped countersinking drill bit, commonly 3/8" in diameter can provide both an appropriate hole for the screw and a hole for a 3/8" bung which can be cut with a plug cutter. Woodcraft is one source of these tools, there are plenty of others too. The plug or bung can be cut from correspondingly colored wood or contrasting wood. After the screw is seated the bung can be glued in with an appropriate wood glue, I use Tightbond III. A Japanese pull saw is often used to cut the bung just a bit higher than the wood surface and then a sander can help you flush the bung with the surface. I hope the attached pictures explain what I have said, if not I have more pictures of the entire process.

Rick Newman

Permalink Reply by Michael Rosso on February 6, 2012 at 11:54am

More than helpful!   Thanks for the suggestion.   I'm very familiar with this technique.   Let's just say I know a lot more about building furniture than building boats!   I'm sure with the help of this site and people like you I'll be able to put together something that looks nice AND floats.

I'm not planning on skimping for materials.  All marine grade AA/AB ply, silicon bronze screws, and I've got a nice stack of 5/4 red oak I can dig into for the appointments.   Google Sketchup is helping me visualize and flesh out the interior.  I just want to make sure I do the really important stuff the right way, the first time!

Permalink Reply by Rick Newman on February 6, 2012 at 12:34pm

Watch out for Red Oak. It has a propensity for soaking up water and then rotting or molding. It's fine when indoors just not so fine when it is in a watery environment. Do a search here or on Wooden Boat Forum for more details. White Oak is a preferable material.

Rick Newman

Permalink Reply by Michael Rosso on February 6, 2012 at 1:08pm

Good to know! 

I love 1/4 sawn white oak, I just don't have a pile of it in my workshop unfortunately.  I want this boat to last with a minimum of upkeep. (for a wooden boat, that is.)  So I'll be sure and heed your advice concerning red oak. 

 

Permalink Reply by Jason Knight on February 6, 2012 at 3:52pm
I am also doing some modeling in Sketchup... Glad to hear I am not the only one : )
Permalink Reply by Michael Rosso on February 6, 2012 at 6:27pm

I don't know what I'd do without Sketchup!   Every single project I've ever done since I downloaded it 5 years ago has started as a sketchup rendering.  It has it's limitations, but considering I have the free version I can't complain. I have only recently began to really utilize all it has to offer.  The only thing I can't figure out how to do is render the hull it'self.  You wouldn't know, would you?  There just seems to be too many different curves.

Permalink Reply by Rick Newman on February 6, 2012 at 9:27pm

I was impressed with the recent illustrations that were done 10 to 14 days ago by Guy. His Excel spreadsheet program might be helpful in generating coordinates for drawings.

Rick Newman

Permalink Reply by Michael Rosso on February 7, 2012 at 5:32am

I had seen those.  Amazing.  I had to stop myself from wanting to learn too much too fast.  Perhaps when I begin my SECOND boat..:)

I'm approaching this one as if I'm going to build more of the same.  I've made patterns of all the frame components from 1/4" MDF so that I can cut them all out using a router, and re-use them if I want. Also, there's no machining marks to sand off.

Permalink Reply by Rick Newman on February 7, 2012 at 7:29am

Micheal, it hasn't taken long for you to get the bug. You have  been on board less than two days and you are already talking about your second boat! Way to go.

Rick Newman

Permalink Reply by Michael Rosso on February 7, 2012 at 7:37am

Rick,

I already had a passion for woodworking so I confess to having a small headstart.  I've never even been in a driftboat so I can't say if it's more fun to use than to actually build one.  But from what I've seen, they sure LOOK like a hell of a lot more fun to use when they're finished than a Morris chair or a bookcase!    

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