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View Full Version : Finally some rascal pics (and a question)



Tom Wilkinson
06-19-2003, 05:24 PM
Ok, I know I am more likely to get answers if I post some boat porn so I offer these up to the gods along with my question.
http://www.imagestation.com/picture/sraid66/pf570410598e6139b597c9784b4c1f1ff/fbe2dbb1.jpg http://www.imagestation.com/picture/sraid66/p35284a9c516f2299f4d91aec2fab8e8f/fbe2dba4.jpg

The boat is a rascal(Ken Basset's design). I am just about ready to start planking and the dreaded CPES question is now coming up. The plans call for seal coating the inside of the ply before planking. I think the main reason for this is to make sanding easier later. The ply can be seal coated and sanded before installation. I have been using west system for all the construction so far but have been thinking of using cpes to seal coat the ply. I have no experience with it bu it seems like it may be easier to apply.
West claims that their best bond comes with new wood to new wood so I am wondering if I should skip the seal coat altogether and plank the boat, then apply a couple of coats of cpes and then paint the interior.
Maybe I should cpes the frame and the ply before planking.
Any recommendations out there or in the whole scheme of things does it not really matter.

[ 06-20-2003, 08:20 AM: Message edited by: Tom Wilkinson ]

imported_Conrad
06-19-2003, 07:21 PM
It does matter. I wouldn't coat the ply with West or any other resin before applying it to the bottom if your intention is to glue it to the stringers. Although it surprises many people, epoxy doesn't stick to epoxy very well, even when sanded and cleaned. So if you want maximum strength you'll have to do your sealing/finishing after the bottom is on, even though it will be more difficult. Personally, I like the CPES/Enamel combination for an interior finish.

Interior overheads are often pre-finished as you've described, but when done properly the areas where the overhead will be glued to the deck or coach roof beams is masked off first so that when the panel is applied it will have the benefit of a wood to wood glue joint. Sounds like a lot of work to me, given the number of stringers on the bottom of your boat. But if you want to try it, pre-fit the bottom, then go underneath and mark along the edges of the battens with a pencil so you'll know where to mask when you pull it off to pre-finish.

Not even 5200 sticks very well to most epoxies, although some have tried it based on the idea that it can better absorb the flexing the bottom will no doubt experience. For my boat, I'd go with the wood/wood joint, no fasteners except for the margins at the keel and chines, and then do the best job of sealing and painting I felt was justified. ;)

Great looking boat- what do you have for power?

[ 06-20-2003, 01:02 AM: Message edited by: Conrad S. ]

Tom Wilkinson
06-20-2003, 08:43 AM
Thanks for the info. I was leaning in that direction. I had planned to plank the boat without seal coating anyting and then use cpes and paint on the interior surfaces after it is all planked. It may be a little more wokr but seemed like I would get superior bonding.

As for power I have an 83 merc 700 with power tilt and trim. I got a steal on one with bad compression in one cylinder but it also came with a spare powerhead so between the two I should get a pretty strong runner and some spare parts as well.

imported_Conrad
06-20-2003, 01:30 PM
You have a pilot's license, dont 'cha?!! Happy flying! :D

JimD
06-20-2003, 01:46 PM
Nice boat, Tom. That looks like quite the stem. Got a close up?

JimConlin
06-20-2003, 03:43 PM
I'd pre-coat the plywood with epoxy, top it with peel-ply, then squeegee flat. When the peel-ply is stripped from the cured epoxy, you have an evenly coated blush-free and eminently bondable surface.

Tom Wilkinson
06-20-2003, 07:26 PM
Originally posted by Conrad S.:
You have a pilot's license, dont 'cha?!! Happy flying! :D Well I have to admit, being a mechanic, I had to go the required 10 hp over what the designer specifies as the maximum for the boat. :D :D

Jim, I will try to get a close up of the stem for you but I think it looks better from a distance ;) That was the hardest part of the project so far.

venetianguy
06-25-2003, 09:29 PM
I agree with Conrad, epoxy definetely works better on untouched wood. You could problably apply it first and sand it before installing the plywood. Another option you have is to apply the resin to the all plywood and apply it before it dries. This way you will have the inside of the botton already protected, do not forget to clean with a brush the resin that exced.
Hope it was understandable. :(
How long did it take you to get at this point ?
Andrea

Tom Wilkinson
06-26-2003, 05:43 AM
It has taken me a year and a half to get to this point but probably only 2-3 weeks worth of work. I have way oo many irons in the fire as far as hobbies go and the boat was pretty low on the priority list but it is moving up on the list.

imported_chris
06-26-2003, 06:23 AM
Tom I built this boat 2001. I glued it together first then sealed it. Its a great boat we have a lot of fun with it.
http://www.imagestation.com/album/?id=4291941191
this is the link.

NormMessinger
06-26-2003, 07:41 AM
Well, ya learn something here every day. Or, get more confused. This is the first I heard that epoxy does not stick well to cured epoxy. I have heard that one does not get a chemical bond after the epoxy has cured. Most of my preconcieved misconceptions about the googue comes from what I learned building my Long EZ and hanging out with other Rutan groupies. So far so good, no delaminations.

I was once scoriated for suggesting lessons learned on an airplane had any relevance to boats but I was not convinced.

Peel ply eliminates both amine blush and provides tooth for a mechanical bond.

So... What's the deal on epoxy not sticking to cured epoxy?

Dale R. Hamilton
06-26-2003, 10:42 AM
yup- agree with Norm. I've never had problem of epoxy sticking to epoxy. And then fresh wood to wood bonds always have the possibility of epoxy soaking into the wood- and you get a glue-starved joint. BTW- I've always liked Gougeon for structural joints- but the System 3 system works better for laminations and coatings. And I use alot of peel ply for all the reasons mentioned. As long as we are opinioning here- in the above example, I would prefit the ply panel over the frames- take it off and then goop it up good with epoxy to pre-coat. For places where the ply has to be really tortured to take the radius- I prefit the panel over stringers covered with plastic or wax paper. Then I epoxy the panel inside and out and fasten it down to the stringers. The expoxy will help the panel retain its tortured shape when its dry.

imported_Conrad
06-26-2003, 11:07 AM
With the increase of high tech boats using epoxy and high modulus fibers, there's been a bunch of research on the strength of what they call seconary bonds- pieces glued or laminated in after the basic hull structure has been layed up. And its been found that epoxy, like the polyester resins, doesn't do a particulary good job of sticking to itself, especially after its been allowed to fully cure. Our sponsor's sister publication, "Professional Boatbuilder" has had a number of articles on this and related issues. Bottom line is, the longer the initial layup has been allowed to cure, the weaker any secondary bonds will be, and while it loves to stick to everything else, epoxy doesn't particulary like sticking to itself.

To ensure good seconary bonds, peel ply has proven to be the best preperation. Second best is grinding with 40/80 grit and a wipe down with solvents. Since the secondary bond is entirely mechanical with no chemicle interaction, a rough, clean surface is essential. Remember, we're talking about going for maximum strength here- a lot of the time, for the kinds of boats we build, this level of preperation may not be neccessary- but the bottom of an over-powered speed boat should get our best efforts! :D

Tom Wilkinson
06-26-2003, 02:29 PM
Chris, Thanks for the pictures. I have seen your album before. Very nice looking boat. Any areas that you had particular trouble with or would do differently?
Tom

Tom Wilkinson
06-26-2003, 04:39 PM
Originally posted by JimD:
Nice boat, Tom. That looks like quite the stem. Got a close up?Here is a better pic of the stem http://www.imagestation.com/picture/sraid67/p5346dd31c414e8e45190ac6c29a3cd89/fbd4b87c.jpg

And just to keep the interest up in this thread, here is a progress pic of the tow vehicle. http://www.imagestation.com/picture/sraid67/p807f014615e00134270d76a3624a8a9a/fbd4bce2.jpg

venetianguy
06-26-2003, 09:05 PM
Once again i have to agree with Conrad.
The West System booklet says pretty clearly that epoxy on epoxy has to be avoided.
The only chance you have is to wash it and send it before you procede with a new application.
Moreover a cured epoxy in only one side of the plywood will force the panel to a curve, therefore stress.
Andrea
PS. Hope my englis wasn't to bad !!!!

imported_chris
06-27-2003, 06:01 AM
I would have made the motor well bigger to acommidate the steering cable better. I did not have the motor when I build the boat. Thats about all. Ken designed it right for me.