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Post by lndseyj on Sept 13, 2021 19:35:15 GMT
To carry on a conversation I started at the Southampton boat show….
I have an option of 2 kits int he UK.
1. Sapele 9mm ply- heavier, stronger, needs less glass/ epoxy…(pricier)
2. Okoume 9mm ply- lighter, needs another coat epoxy
Any views on performance v weight v seaworthiness? I expect the answer is complicated.
there appears to be no strong view out there…even Fyne the kit maker wasn’t sure…although probably in the end, favoured okoume and extra epoxy.
Any comments gratefully recieved
Lindsey
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brucel
Junior Member
Posts: 54
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Post by brucel on Sept 14, 2021 12:17:05 GMT
Hi, as far as I have read the only way to reduce the amount of lay up is with 10mm ply. If you type 10mm into the search button on the forum it will bring up a couple of early conversations about it. Mine is coming 9mm occume.
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Post by lndseyj on Sept 14, 2021 19:16:15 GMT
The epoxy requirement is reduced because the wood is denser ( apparently!)
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Post by cas206 on Sept 14, 2021 22:55:10 GMT
My completely uninformed opinion is that:
Weight: The two kits are probably designed to make about the same weight hull to meet the requirements. So less glass/epoxy (and weight) makes sense for denser wood. So if the kits make the boat to requirements, weight difference should be a non-issue (i.e. about same weight).
Seaworthy: Stronger sounds better. At face value, it would appear to be a question of strength of the composites (stronger wood + lighter fiberglass skin) vs (lighter wood + thicker fiberglass skin). I leave that up to manufacturers and engineers. (I'm taking you at your word that the sapele is stronger than the Okoume.) As a backyard builder, especially first time builder, I would prefer to put my safety in the hands of the plywood manufacturer and go with stronger wood so that less percentage of the strength of the composite relies on my fiberglass skills.
Performance: If same weight, same performance, would be my best guess.
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Post by captdan on Sept 16, 2021 2:48:29 GMT
Hi,
I'll chime in here with some of my experience and what I used for the construction.
I purchased the more expensive and heavier Meranti plywood which allowed me to use less fiberglass on the hull compared to the Okume. There was alot of conversation that we had about this last summer about what was the best and what combination would lighter or heavier. On a personal note, I feel quite comfortable knowing that there is a high quality plywood under my feet along with a good bit of fiberglass cloth to ensure more durability. I dont have any experience with the alternative plywoods so I cant compare the 2. One thing that I do suggest is that all of you check out Gregory Martell ( Hull # 71 ) blog and his posts here on the Forum. He is a professional boat builder with decades of experience with all of this. He has been a great contributor to this group of builders as well. Last summer, one of the first things that he did was a sample of each species of plywood and the required layups of fiberglass. He calculated the weight of each and did an estimate on the difference in weight of the completed boat based on his findings. I believe the "hardwood" plywood layup sample (such as Meranti) was slightly lighter overall - but not by much.
Now that I have my boat in the water and have sailed it a bit, I can tell you that this boat is designed to be very robust and very seaworthy.
Cheers,
Dan
Hull #20
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martellmarine
Junior Member
Husband & wife team building boat #71.
Posts: 61
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Post by martellmarine on Sept 21, 2021 5:14:14 GMT
Yes, I did do a comparison of BS1088 Okoume and its specified fibreglass layup and BS1088 Meranti and its specified layup. A Meranti hardwood hull and deck comes out a little lighter based on the samples I did (your miles may vary, so do a sample if you can). I have bought Meranti for my hull for a few reasons.
1. Finished product will give a slightly (a few kilos) lighter hull...
2. There is little over half of the epoxy resin and fibreglass required for the layup so the cost for that vs the Okoume hull will be approx 40% or so less for that material.
3. Meranti is about 10% less in cost than Okoume here in New Zealand.
4. The time it takes to apply the fibreglass on a Meranti/Hardwood hull is less that Okoume because there is simply less to do...
Other things to consider...
5. If new to fibreglassing, then the skill required to apply the glass skins to a Meranti/Harwood hull is easier to learn and cope with (providing you choose the right materials) than for the Okoume hull.
Hope that helps...
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brucel
Junior Member
Posts: 54
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Post by brucel on Sept 22, 2021 21:22:09 GMT
as I did not know where to look for this info, I thought I should post it for others.
builders update 2 with laminating information
BnB google doc has good table to follow and an explanation from Janszu. Amounts do not agree with builder update 2 for build up.
(ps thanks Greg for pointing me in the right direction)
Attachments:
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Post by marcoab on Oct 6, 2021 10:17:08 GMT
i made the same question on the fb blog...looking for the best answer and the best choice
Hi to everyone!!! I'm almost ready to build my 5.80 "Bandolero 93"!! I will make you a lot of question for sure!!
First! Which plywood did you choose? I mean which are the differences between sapele and okumene? And in terms of weight which are the differences including the fiber glass that I will use?
Many many thanks
marco
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brucel
Junior Member
Posts: 54
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Post by brucel on Oct 6, 2021 18:28:59 GMT
Hi Marco, I am using 9mm occume as that’s what I can get that is certified to a recognized standard here in western canada. Greg Martel has written a number of good points on this subject, I think you can search his post across the forum.
I would have gone with 9mm hardwood (meranti) If it was an option for me as it’s less work on the fibreglass lay up.
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Post by lndseyj on Oct 12, 2021 20:02:21 GMT
Looking at the advice above sapele would seem better than okoume as it is even “stronger” and has a slightly lower specific gravity than red meranti
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martellmarine
Junior Member
Husband & wife team building boat #71.
Posts: 61
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Post by martellmarine on Oct 14, 2021 3:01:54 GMT
Looking at the advice above sapele would seem better than okoume as it is even “stronger” and has a slightly lower specific gravity than red meranti Just make sure before committing to your plywood of choice that the supplier can give you a document or certificate supporting it being made to BS1088 or equivalent marine grade standards. You will need this for class certification. Cheers. |
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