MI Malahini questions

Designs for inboard or outboard power

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PeterG
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Re: MI Malahini questions

Postby PeterG » Wed Jun 13, 2018 12:45 pm

Like Matt said, choose wisely. You can consider the grain of the wood, whether it's vertical grain (growth rings parallel to the edges) or flat sawn (growth rings parallel to the wide faces). One boatbuilding book I have says to use flat sawn wood for chines and sheers, to avoid splitting when planking fasteners are installed, which can happen in vertical grain. From what I've seen, flat sawn chines and sheers seem to split or break much more easily. I used the clearest vertical grain wood I could find for my Malahini. I have yet to bend them into place so the jury is out on whether my plan will work.
Murphy's Law: Anything that can go wrong, will go wrong.
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footer
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Re: MI Malahini questions

Postby footer » Wed Jun 20, 2018 4:16 am

Question about fiberglassing my hull. Which way do you recommend; epoxy the hull first, let dry, sand, then lay fiberglass then epoxy? or lay fiberglass then epoxy? I've seen videos on both ways, but what would you say is best?

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DrBryanJ
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Re: MI Malahini questions

Postby DrBryanJ » Wed Jun 20, 2018 5:46 am

Footer: I laid on the fiberglass then rolled on the epoxy. I did not see any problems. Others have said they felt the raw wood soaked up too much epoxy and the fiberglass didn't fill completely. I think which every way you choose will work fine.
Bryan

Building a malahini "Mona Lisa"

My wife said "If I build a boat, she's getting a divorce."

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hoodman
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Re: MI Malahini questions

Postby hoodman » Wed Jun 20, 2018 7:58 am

I think it's probably best to do a thin seal coat of epoxy, let it cure, and sand smooth with 80 grit before you lay the cloth on. Doing it without is probably fine too but it does seem like raw plywood soaks up a not insignificant amount of epoxy. That way when you get to the cloth you're only trying to saturate the cloth and not dealing with the plywood wicking epoxy down through the cloth.

footer
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Re: MI Malahini questions

Postby footer » Fri Jun 22, 2018 4:22 am

Thanks guys. I appreciate the input. I went ahead and tried laying the cloth and epoxying over it just to see how that would go. I worked the epoxy in liberally and it seemed to go well. I have to go back over it with another coat of epoxy. So, I'll sand it and put on the other side layer of fiberglass. Then I'll go back and sand the whole bottom and put on another coat of epoxy over the whole bottom. Then it's on to the sides.
June 20, 2018
Attachments
IMG_3592[1].JPG
Malahini. Fiberglass epoxied, first coat. Pinkish tan stuff is Quickfair. 6/20/18
IMG_3593[1].JPG
Malahini. First sheet of fiberglass and epoxy. 6/20/18
IMG_3581[1].JPG
Malahini. Fitting fiberglass sheet. 6/19/18

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DrBryanJ
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Re: MI Malahini questions

Postby DrBryanJ » Fri Jun 22, 2018 5:10 am

footer: I don't think you need sand between coats of epoxy. You will probably need three coats to fill the weave. THen you start sanding
Bryan

Building a malahini "Mona Lisa"

My wife said "If I build a boat, she's getting a divorce."

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hoodman
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Re: MI Malahini questions

Postby hoodman » Fri Jun 22, 2018 5:11 am

Looking good. Don't sand too much between coats and get into the cloth. You can do several coats without sanding if you don't wait until it's fully cured.

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Bill Edmundson
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Re: MI Malahini questions

Postby Bill Edmundson » Fri Jun 22, 2018 5:48 am

When it's dry too the touch and can dent it with your thumbnail you can get another coat on it without sanding.

Bill
Mini -Tug, KH Tahoe 19 & Bartender 24 - There can be no miracle recoveries without first screwing up.
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PeterG
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Re: MI Malahini questions

Postby PeterG » Fri Jun 22, 2018 8:42 am

Ditto what Bryan, Matt and Bill said. When you get to the sides, you'll need a little extra attention to keep the epoxy resin from running and sagging before it fully gels. Not a huge problem, just be aware it could happen, may need some occasional extra spreading to keep it in place. Great looking work so far! I picked up 60" wide cloth for my Malahini, to do both port half and then starboard half in one step each. If that seems too ambitious I can rip it down to two bottom pieces and two sides.
Murphy's Law: Anything that can go wrong, will go wrong.
Griffin's Law: Murphy was an optimist.

footer
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Re: MI Malahini questions

Postby footer » Thu Jun 28, 2018 3:48 am

So, I am a bit concerned about sagging on the sides when i put my fiberglass on. I noticed it on the bottom and if it does that there, it will definitely do it on the sides. I have been using system three slow cure epoxy so far. Do you guys think maybe the fast cure would work better for sides to help with the sagging issue?

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hoodman
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Re: MI Malahini questions

Postby hoodman » Thu Jun 28, 2018 4:47 am

Sagging on the weave fill coats I assume? It would mean you're trying to put too much on at once. You might be able to get away with fast for filling the weave but definitely not for wetting out the cloth. Whatever amount you used to wet out the cloth, you'll only need about half that for the first weave fill coat and maybe even less for the second. Keep spreading it around with a roller so you're sure it's evenly coated. It's not like paint, you can keep rolling it and re-distributing around for quite a while. I would stick with slow hardener especially with the warm weather.


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