HMD 21 starting - help

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duysall83
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HMD 21 starting - help

Post by duysall83 »

Hello Evan and whole forum members, shelter is built. Materials for jig and all supplies including biaxial cloth etc ready except plywood sheets.

For the plywood i plan to use okume but it's really expensive. 1) Is it ok to build the hull with okume and do the rest with marine grade beech?

I've read things about beech on the web regarding rot and durability issues so i was confused but what i see after many research in the market i see that it's common here in Turkey to use beech for boat building. Can it be because it'll be encapsulated fully with epoxy and glass? 2) That fact eliminates weak points of beech? What do you know or think about this beech issue?

One more question for now, normally hull sides are laminated 3 parts. 3) May i laminate 5 parts in the required way in order to save some okume sheets?

Thanks in advance, i'll need support from all members. First time builder, please forgive my ignorance and warn me at any stage of the build.

Regards, Duysal
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fallguy1000
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Re: HMD 21 starting - help

Post by fallguy1000 »

Welcome and happy building.

I will give Evan a chance to answer.

The only thing I will say is ply encapsulated in 6oz glass and epoxy requires at least one extra neat coat to avoid water issues. Since I don't know the design well; I will bow out of answering where a different grade of lumber would or not work.

As for increasing joints to save lumber; it seems that would not be the route I'd go. The hull is, generally speaking, not the major cost in a boat; so saving money on it is not the way I'd go.

If you have excess okume from the hull; those panels can be used elsewhere and/or scarfed back up into bigger panels.
My boat build is here -------->

viewtopic.php?f=12&t=62495

duysall83
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Re: HMD 21 starting - help

Post by duysall83 »

fallguy1000 wrote: Mon Dec 07, 2020 8:53 am Welcome and happy building.

I will give Evan a chance to answer.

The only thing I will say is ply encapsulated in 6oz glass and epoxy requires at least one extra neat coat to avoid water issues. Since I don't know the design well; I will bow out of answering where a different grade of lumber would or not work.

As for increasing joints to save lumber; it seems that would not be the route I'd go. The hull is, generally speaking, not the major cost in a boat; so saving money on it is not the way I'd go.

If you have excess okume from the hull; those panels can be used elsewhere and/or scarfed back up into bigger panels.
Thanks fallguy, already bought okume 👍

Cowbro
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Re: HMD 21 starting - help

Post by Cowbro »

I'm excited to see another HMD being built. I assume you plan to scale up the 19 by 10% in all dimensions. I think that is going to be an awesome boat. Make sure you keep us updated on the progress.

duysall83
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Re: HMD 21 starting - help

Post by duysall83 »

is it ok to use microfiber instead of woodflour for the epoxy putty?

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Evan_Gatehouse
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Re: HMD 21 starting - help

Post by Evan_Gatehouse »

If it is ground very fine it is OK. But usually it is too fine. If you can't get woodflour a mix of Colloidal Silica ("Cab-O-Sil") and microballoons is fine.

I'd be vary cautious of using beech in open areas of the boat or parts exposed to the weather. Inside furniture and frames, maybe OK, but not cockpit sole or cabin sides.

I have some clients in Turkey (medium size shipyards). I can ask them what plywood they buy and where they get it if that would help.
designer: FB11/GV10,11,13/ HMD18/
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Evan_Gatehouse
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Re: HMD 21 starting - help

Post by Evan_Gatehouse »

One more question for now, normally hull sides are laminated 3 parts. 3) May i laminate 5 parts in the required way in order to save some okume sheets?
Do you mean short pieces glued together to make longer pieces for the hull? Yes, that is OK.
designer: FB11/GV10,11,13/ HMD18/
SK17,MM21/MT24

duysall83
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Re: HMD 21 starting - help

Post by duysall83 »

Evan_Gatehouse wrote: Sat Dec 12, 2020 6:15 pm If it is ground very fine it is OK. But usually it is too fine. If you can't get woodflour a mix of Colloidal Silica ("Cab-O-Sil") and microballoons is fine.

I'd be vary cautious of using beech in open areas of the boat or parts exposed to the weather. Inside furniture and frames, maybe OK, but not cockpit sole or cabin sides.

I have some clients in Turkey (medium size shipyards). I can ask them what plywood they buy and where they get it if that would help.
Thank you Evan,

Already bought some beech too at least i can use for frames as i understood.

Btw, woodflour is sth i can ask from any timber workshop, carpenter etc? It's not a commercial special product with any brand, right?

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gstanfield
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Re: HMD 21 starting - help

Post by gstanfield »

No brand on wood flour. It’s just really finely ground wood, like a very fine sawdust. My first boat was built with pecan flour made by grinding pecan hulls into dust. I thought it was a brilliant way to use the otherwise wasted hulls from pecans.
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fallguy1000
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Re: HMD 21 starting - help

Post by fallguy1000 »

Wood flour is not sawdust.

You will want finely ground particulate or the thickened resins for fillets will clump and be very hard to work.

You want flowable fillers or it becomes very difficult to apply bonding tapes to the seams over uneven areas and impossible to sand a fillet that is decorative.

In Turkey, certainly fumed silica is available if you cannot find a commercial grade of wood flour.

If you know about a place that uses filter bags in dust collection systems; sometimes those fines are suitable, but you might need to run through a sieve if not pure fines.
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