LM18 Houston Tx

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pee wee
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Re: LM18 Houston Tx

Post by pee wee » Fri Aug 28, 2020 8:55 am

You've gotta love sanding!! :roll:

You want to sand as little as necessary: first you sand off the binding threads of the biaxial fabric, that's only there to hold the fiberglass together until it's bonded to the hull. You're going to want to put that random orbital sander to the side for a while and get/make a long board . . the goal is to make the hull surface fair and with that relatively small pad you're just going to float over humps and valleys when what you need to do is identify the low spots and only apply fairing compound there. Put some good and coarse cloth on it, like 60x or even 40x, you don't want to waste time making it smooth until you get close to fair. Run it across the surface at a 45 degree angle to the centerline, then switch it around to the opposite angle. Don't apply fairing compound to the high spots, you'd only be wasting compound and energy sanding. When you think you're getting close you can use a guide powder or light mist coat of spray paint to make it obvious where it's still low, as the long board won't sand the low spots.

The less material and energy you waste, the quicker it will go and you'll get the results you are looking for. Expect the first coat of primer to reveal some spots you didn't know needed one more pass. You may want to save the QuickFair for late in the fairing process and use something less expensive to fill the deep areas.


Hank

ericwensel
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Re: LM18 Houston Tx

Post by ericwensel » Fri Sep 04, 2020 2:26 pm

I hope to make some progress over the weekend. Here is my plan. Comments and suggestions appreciated.

Fairing.

I sanded the fiberglassed hull bit more. I pretty much have the binding thread knocked down everywhere.
I plan to coat the hull with a fairing mix but mixed to a ketchup consistency rather than peanut butter consistency. i am thinking this will fill the weave and not build up on already high spots. I will use the BBC mix.
While still tacky, i am thinking i will add a thicker fairing mix to the known low spots.
i have low spot at near transom and keal (1/8") and then where the fiberglass tape edges are (<1/8").
I will then wait until the next day and sand with a 30" long board and then check for high / low spots again. Hopefully then i will have few enough areas with low spots and i can use QuickFair to finish.


Rubrail

i traced the side panels at the shear line to a roll of paper so i could use it to trace and cut a rub rail and make it easier to bend to the shape of the shear line. I had intended to use a sheet of Okoume to make 3 layers of rub rail. I am not thinking i might want to finish the rub rail bright instead of painted. If so, i am thinking i will need cut from solid wood strip (perhaps still 2 or 3 layers). Using the trace to eliminate the need for compound curve i think would still apply - although i will waste a lot more wood.

Flipping

I am thinking that i will flip the boat after getting close to fair and installing the rub rail. It seems it would be right to glass the inside and install the stringers before flipping the boat back over and doing any final fairing, priming and painting. Would I be making a mistake by taking this approach.?
I know a lot of people paint before flipping.

Lastly after final fairing, i was going to coat the entire boat with unthickened epoxy before priming and painting. I have seen this step suggested in a few places.

Browndog
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Re: LM18 Houston Tx

Post by Browndog » Fri Sep 04, 2020 5:40 pm

Bright finished Okoume looks great. Would be fine for the rubrails, but try to get all of the top layer pieces from the same sheet or you will get color variations.

Put a fillet on the bottom of the rubrail. Consider putting the deck and gunwales on top of the rubrail then round everything and put a layer of light cloth wrapping over the deck, gunwale and rubrail.

I’m an advocate of the fiberglass, sand, fair, prime and paint process. It has worked well for me and I think it is quicker and certainly easier to flip only once.

cape_fisherman
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Re: LM18 Houston Tx

Post by cape_fisherman » Fri Sep 04, 2020 5:57 pm

I would suggest you finish fairing, priming, and even painting before flipping the hull. There is no need to flip it back & forth. Just do it all & be done with it.

Cbuf
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Re: LM18 Houston Tx

Post by Cbuf » Fri Sep 04, 2020 9:37 pm

I third the fill, fair, prime, and paint.
Cbuf
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ericwensel
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Re: LM18 Houston Tx

Post by ericwensel » Sat Sep 05, 2020 3:16 pm

Thanks for the suggestions. I will stick with Okoume for the rub rail and will completely finish the outside before flipping as suggested.

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Re: LM18 Houston Tx

Post by Jeff » Sun Sep 06, 2020 7:23 am

Excellent decision Eric!!! Jeff

ericwensel
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Re: LM18 Houston Tx

Post by ericwensel » Mon Sep 07, 2020 10:50 pm

A little more progress this weekend.

I applied a slightly thickened epoxy (ketchup consistency), then sanded a bit before applying another thicker fairing mix with focus on the known low spots such as around the tape edges. I still have a good bit of work to do.

I think my strategy will be to work on two areas each day working my way from stern to bow in 4' increments.
Area 1 - sand an area where i added fairing compound to low spots on previous day
Area 2 - add fair compound to low spots in new small area
Breaking it up like this is probably terribly inefficient but keeps me from getting to worn out and give me some learning as i go. I am sure i will get better along the way.

I also cut and dry fitted the rub rail. It is ready to go and fits nicely. I cut along the shear line so i am not having to force a compound curve. I am leaning toward gluing together before installing. As it is not a compound curve, i think it will still bend nicely.

For the fairing mix, i am using the BBC fairing mix (50%) + wood flour (50%). I would love to use 100% fairing mix but i was try to make it last. I am sure it makes it harder to sand but also not near as smooth to apply. Also, i have to be more careful with runs.

Below are some pictures of progress.

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After a morning of sanding with a 30" and 16" fairing board i gave myself a break and switched to the rub rail. I have the first layer of the rub rail dry fitted (shown). The other layers are cut, dry fit and ready to go.

Image
This is a pretty ugly picture. The hull bottom near the transom seems pretty flat for the first 4 feet or so on each side but i have a low spot (1/8") in the middle starting a few inches forward of the transom and lasting about 18". I partially filled but my last batch of fairing mix ran a little short and i just ran out of steam.

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Re: LM18 Houston Tx

Post by Browndog » Tue Sep 08, 2020 6:19 am

I used three layers of Okoume to make the rub rail on the FS 19 that I built and laminated them on the boat with staggered joints for each layer.

Based on my experience, you might want to build a small sample of the rubrail to see if a multiple layer laminate can be applied in the way that you propose.

Just putting on one layer at a time was a challenge for me even in the mostly straight areas.

You also need a ton of clamps to keep everything from sliding around. I had to do one side at a time despite having dozens of clamps. Took me a while to laminate three pieces on each side, fill in any voids and add a fillet to the underside.

ericwensel
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Re: LM18 Houston Tx

Post by ericwensel » Wed Sep 23, 2020 12:43 am

I have not had a good opportunity to put in a long day on the boat in a while but have been slowly fairing the hull. As suggested, i put away the orbital sander and have been using the fairing board. The low spots are getting harder to find and shallower. I am feeling a lot better about finishing this step. I posted some pictures below. I am going to continue to work on fairing another two weeks. I have a Elk hunt coming in a couple weeks and i decided i would use that as a deadline to finish fairing so when i return i can finally move on to another task.

My next steps are sharpening the chines and adding the skeg.

For the chines i have seen a few variations of building a dam using wood and packing tape. I am thinking of mixing a epoxy/wood flour/chopped fiberglass mix. Suggestions?

For the skeg, i have a supplier nearby (Houston Hardwoods) that can source most woods. I had heard Ash is a good choice. I intend to fillet and then layer the skeg with fiberglass. I noticed that many add the skeg before fairing. Too late for me. Since i already faired, i am thinking i need to grind back the quickfair before bonding. Is it too late to glass the skeg. Suggestions?

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