modified malahini

Designs for inboard or outboard power

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DrBryanJ
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Re: modified malahini

Post by DrBryanJ » Mon Aug 13, 2018 2:41 pm

I'm not necessarily concerned about bolt holes being below waterline, but really how low it looks like the engine is in the water. I said I don't know much about motors, maybe it isn't a problem at all.
unnamed (3).jpg
The waterline is at the bottom of the tape. Is that too much engine to have in water before starting? I guess the 25" would still have the same amount?

Also, From the edge of the motor well to the waterline is only 7". Is that a concern? The longer shaft would make it 12". Depending on how deep I have to make the motor well, the drain holes at the bottom of the well will be very close to the water.
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Roberta
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Re: modified malahini

Post by Roberta » Mon Aug 13, 2018 2:47 pm

The cavitation plate on the motor should be about even with the bottom of the keel.

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PeterG
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Re: modified malahini

Post by PeterG » Mon Aug 13, 2018 3:19 pm

Your waterline on your motor looks about right, maybe slightly higher up than "usual" on a 20" transom, but so much depends on the hull shape and size for the actual waterline. A big part of the uncertainty with your boat comes from the added hull depth with the vee bottom. If your final hull weight is close to the original design, your waterline will be significantly further down the transom. The height of the transom cut above the water may be a concern but if your motorwell in front of the transom goes to the deck and is angled like intended, you should be be ok. The risk with a lower transom cutout is your wake coming up over the transom when you cut the throttle. The motorwell catches whatever splashes into the boat and drains it out the transom. A higher cutout with the longer 25" shaft gives you more margin against this but I don't see yet where you have to make a big change. Just make sure the cavitation plate of your motor is even with the lower point of your transom, like Roberta said. Your motor wants the 20" from lower point to the cutout. You may need some naval architectural assistance if you want to get an estimate where your waterline will be.
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Brad Tucker
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Re: modified malahini

Post by Brad Tucker » Mon Aug 13, 2018 3:54 pm

If that is your waterline, the engine height above the water isn't an issue. Looking at the motor mount in the picture and the missing paint, it looks like your waterline may actually be lower than it was previously....

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DrBryanJ
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Re: modified malahini

Post by DrBryanJ » Mon Aug 13, 2018 5:02 pm

Thank you everyone for your replies. I think I will continue as before, but keep my eye open for a 25" shaft e-tec. I wouldn't make any changes until after I flip the hull, so it gives me some time to mull everything over.
Bryan

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Re: modified malahini

Post by DrBryanJ » Wed Aug 29, 2018 11:57 am

All right. So I think I'm ready to put on bottom paint. Everything primed and sanded to 220. I am using WR-LPU. I don't have spray equipment, so I will be rolling and tipping. My plan was to put on 4 coats, let it cure then sand starting with 600. I just went back and read Bayou Bengal's post about painting
if you really want to roll it you can, just realize you're going to need to block sand it out (with either 220 or 320) between every couple coats. Once you build up enough that it blocks out very easily without sanding to the primer in any spots, you'll put on 2 or 3 more coats and then start blocking sanding with 600 to 800 (even higher if you're a good sprayer) and work up through the grits to 1200.
. So, now I guess I should do only two coats, sand and repeat. Questions are, 1) How long do I need to wait before sanding? 2) When tipping, is a fine brush or a foam brush better?
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hoodman
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Re: modified malahini

Post by hoodman » Wed Aug 29, 2018 12:08 pm

I've used a cheap foam brush and a 2.5" Purdy XL. I think the Purdy does a much better job with tipping. Plus, if you have any areas you can't roll it is far superior to the cheap foam brushes. I have an area between the waterline and the spray rails that really couldn't be rolled. So I brushed it and it looks exactly the same as the areas that I rolled and tipped. If I could offer any advice it would be to not stress too much about how the bottom of your boat looks. Nobody's going to look at it after the flip. I would go ahead and do four to five coats and then wet sand and polish if you must. Save your energy for the topsides. The key with WR-LPU is moderate temps and high relative humidity. Cool rainy days are great for the stuff. Or dewy mornings and evenings. You can re-coat in an hour most of the time. So you could have 5 coats on in half a day. If you want to sand you need to probably wait overnight. If you try to sand too early it will come off in little ribbons.
Matt

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DrBryanJ
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Re: modified malahini

Post by DrBryanJ » Wed Aug 29, 2018 12:18 pm

It is 95 today, but Saturday is supposed to be low 70's and rainy. That is why Saturday was my day to paint. The WR-LPU literature says to wait 4-6 hrs between coats, so if I start early, I can get 3 or 4 coats done.
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hoodman
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Re: modified malahini

Post by hoodman » Wed Aug 29, 2018 12:37 pm

Look at the can. It says, "Recoat: Apply additional coats of WR-LPU when the previous coat is dry to the touch (45-60minutes at 77F and 50% relative humidity)." It will take longer with more humidity but not 4 hours.
Matt

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DrBryanJ
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Re: modified malahini

Post by DrBryanJ » Wed Aug 29, 2018 12:58 pm

Matt\: I'll check the can when I get home. I was reading the literature that is on their website. I have the same brochure at home, but don't remember seeing the 4 hr wait time between coats. Maybe that has changed.
Bryan

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hoodman
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Re: modified malahini

Post by hoodman » Wed Aug 29, 2018 1:13 pm

I think maybe what you read was you need to wait 4-6 hours before sanding.
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DrBryanJ
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Re: modified malahini

Post by DrBryanJ » Wed Aug 29, 2018 1:20 pm

Matt: Here is the quote from the System 3 website
When brushing, fi rst spread the material out, then work back
into the wet material with long, slow strokes. When rolling,
use the short-nap roller mentioned earlier, and then go back
over the wet coat lightly, with a synthetic fi ne bristle brush,
to pop any bubbles. This is called “rolling and tipping.”
Allow paint to dry 4-6 hours before applying the next coat. 2
coats can be applied the same day.
Bryan

Building a malahini "Mona Lisa"

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Re: modified malahini

Post by Hercdrvr » Wed Aug 29, 2018 1:30 pm

My .02 on bottom paint, thin the paint enough so it will level out after you tip it. I appy as many coats needed to cover for color, with no primer showing through. I won’t be able to critique your work because I’ll never see it.
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DrBryanJ
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Re: modified malahini

Post by DrBryanJ » Wed Aug 29, 2018 1:38 pm

I just spoke to System 3 and this is their response. They now recommend waiting 4-6 hrs minimum between coats. Applying second coat sooner will cause paint to dry quicker and may make it difficult to tip and keep a wet edge. You can recoat before 24 hrs. Longer then 24 hrs requires sanding.
So, I can do 2 or 3 coats Sat. and 2 or 3 Sunday.
Bryan

Building a malahini "Mona Lisa"

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jenko
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Re: modified malahini

Post by jenko » Wed Aug 29, 2018 2:24 pm

I used 316 stainless (that is generally considered marine grade)

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