Alternate build methods?? long winded post, you've been warned

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Lakesurfer
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Alternate build methods?? long winded post, you've been warned

Post by Lakesurfer »

Hello,

This will be a long winded post with my main interest being alternatives to wood core, alternatives to expensive marine foam and solid fiberglass construction. Let’s get a few things ironed out first.
1. I have several years of experience with composite manufacture and repair in the aviation industry. I have all my own composite manufacturing tools for wet layup and vacuum bagging.
2. I have about zero experience with boat building.
3. I believe the wood core plans are solid and tested and would last for years but my brain will never get past having wood in my boat. For me a wood boat is like having a check engine light on in your car for something like your gas cap being cracked open. You know its fine but it will always bother you. I do not mean to sound like a spoiled brat but if wood core was the only way to go, I wouldn’t bother building a boat.
4. Im not concerned with the overall weight of the boat.
5. The boat would be used mostly as a solo fishing boat in the mid-west coast Florida flats and the occasional island hopper with my wife and daughter. And if im honest im sure she would only let me out a couple times per month anyway so at the end of the day it will be a light use boat.
6. Sometimes I start projects and sometimes I finish projects.
Here goes,
I’ve recently purchased the ph16 and ph15 plans with the intention to study and one day build. After many measurements of the boats, trailers and my garage I’ve determined the PH15 is a great fit for me and im obsessed with the design so it works out well. With wood core being out of the question for me I’ve been looking at foam and I priced it out at close to $3,000, now add everything else and it adds up quick. Im not opposed to spending money but im opposed to wasting it. Is the benefit of the core materials in a boat to cut weight compared to a solid laminated? I understand weight has a direct relationship with performance but im afraid my boating skills are far to low to understand what a good performing boat should feel like. So if I built a heavy boat I don’t care if it drives like a bus because im just not that kind of guy and If im on the water im happy.

1. Would a solid laminated hull work? I know it won’t work as good as the cored design.
a. With epoxy and glass what would my laminations schedule look like? How many more layers of cloth would be required to replace the foam/wood?
b. With a solid laminate, considering cost and my very little concerns about weight should I just consider a polyester hull?
2. In a lot of composite airplane parts the strength is on the fiberglass skin or the carbon and the foam core is only used to create and hold the shape of part. That being said. The stringers on the PH15 foam version use a 5lbs density foam and 2 layers of 12 oz cloth on each side plus tabbing. Is there a formula to consider when using say a 2lb foam. Meaning if I had a 2lb foam, what lamination schedule would yield the same of similar properties as the 5lbs? 3 layers of 12oz glass plus tabbing with 2lbs core? Or can I increase the width of the stringers and therefore increase the surface area in total, resulting in stronger stringers.
For now these are my main questions. I don’t want to come across as a jerk but im really not interested in hearing negative comments or that this or that cannot be done, Im looking to open a discussion on building a boat and the different techniques that could possibly be used.

I appreciate the conversation and incites.

thank you

-Mark

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Re: Alternate build methods?? long winded post, you've been warned

Post by jacquesmm »

This is the answer:
https://boatbuildercentral.com/product/ ... lans-ph15/

I will elaborate. The PH15 was designed for foam sandwich, the plywood version is an option.
https://www.boatbuildercentral.com/Stud ... _STUDY.pdf

The very first PH15 was built in foam sandwich, in the old bateau.com shop. We used Divynicell foam.
A single skin version (all fiberglass, no foam) would be heavier than the plywood version.
Calculated weights are listed in the study plans, see the link above.
The BOM for foam sandwich is also listed. The type of glass and number of layers are listed in the plans.

We also built a PH16 in foam, an hybrid PH18 and many more. I can supply foam sandwich specs for most of our designs.
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http://boatbuildercentral.com

silentneko
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Re: Alternate build methods?? long winded post, you've been warned

Post by silentneko »

LS I think you are missing something on the performance side, Draft. The heavier you are the more you draft, and the deeper the water you will need to not only float, but to get up and plane out.

You will also most likely spend more making the plug and thickening the lamination for strength then you would on the cored version. There are some price conscious foam and pvc cores out there now that will help you out, like carbon core. Good luck.
Built: 15ft Skiff, 16ft Skiff, Modified Cheap Canoe, and an FS17.

Lakesurfer
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Re: Alternate build methods?? long winded post, you've been warned

Post by Lakesurfer »

silentneko wrote: Fri Oct 30, 2020 11:07 am LS I think you are missing something on the performance side, Draft. The heavier you are the more you draft, and the deeper the water you will need to not only float, but to get up and plane out.

You will also most likely spend more making the plug and thickening the lamination for strength then you would on the cored version. There are some price conscious foam and pvc cores out there now that will help you out, like carbon core. Good luck.
For sure I agree with ya here,

Im really trying to find a way to avoid building an expensive (relative) home built boat. my confidence and abilities, I believe are up to the challenge but i can fade in and out of projects at times. as it stands with the divinycell foam, im looking at, maybe $6,000 for a completed hull?

Ive been looking at carb core for a while now and it looks like a potential option for PVC foam and even seemingly better is there carbon core PE foam. its a polyester foam in 5lbs density that is said to have better properties than PVC and PU foams and is quite a lot cheaper. I've been using US Composites epoxy resin for a long time without issues and can be had for a little over $600 for 10 gallons. so if the PE foam is what it is and with the cloth and epoxy i could be looking at maybe around $3,000 for a completed hull, ish. still have a lot of questions to answer though.

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cape man
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Re: Alternate build methods?? long winded post, you've been warned

Post by cape man »

Good wood (BS 1088), sealed in epoxy is not going to rot. All the failures in wooden boats is from poorly sealed wood. My boat is going on 12 years and I don't ever worry about the fact that the core is marine plywood. The rhetoric from manufacturers on "no wood" has been very successful with guys like you, but has blinded many to the reality that it all depends on how the wood is used and treated.
I know I'm not changing your mind, but there's a lot of boats built here that prove you wrong in your fears. That said, I look forward to seeing a foam sandwich PH15 being built in the area. Hope you pull the trigger and post a build thread. There are lots of foam sandwich builds here as well that will help you.
The world always seems brighter when you've just made something that wasn't there before - Neil Gaiman

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Re: Alternate build methods?? long winded post, you've been warned

Post by Chenier »

Lakesurfer wrote: Fri Oct 30, 2020 10:05 am 4. Im not concerned with the overall weight of the boat.
That's like not being concerned with the overall weight of an airplane. Boats operate in a different medium, but weight and balance are still important in the design. When you get the PH15 planing, it's essentially "flying" on the surface of the water. Just like an airplane, extra weight in the hull is going to mean either less usefull load or more power (bigger engine) to get the same performance. TAANSTAFL.

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Re: Alternate build methods?? long winded post, you've been warned

Post by gstanfield »

Lakesurfer wrote: Fri Oct 30, 2020 1:57 pm
silentneko wrote: Fri Oct 30, 2020 11:07 am LS I think you are missing something on the performance side, Draft. The heavier you are the more you draft, and the deeper the water you will need to not only float, but to get up and plane out.

You will also most likely spend more making the plug and thickening the lamination for strength then you would on the cored version. There are some price conscious foam and pvc cores out there now that will help you out, like carbon core. Good luck.
For sure I agree with ya here,

Im really trying to find a way to avoid building an expensive (relative) home built boat. my confidence and abilities, I believe are up to the challenge but i can fade in and out of projects at times. as it stands with the divinycell foam, im looking at, maybe $6,000 for a completed hull?

Ive been looking at carb core for a while now and it looks like a potential option for PVC foam and even seemingly better is there carbon core PE foam. its a polyester foam in 5lbs density that is said to have better properties than PVC and PU foams and is quite a lot cheaper. I've been using US Composites epoxy resin for a long time without issues and can be had for a little over $600 for 10 gallons. so if the PE foam is what it is and with the cloth and epoxy i could be looking at maybe around $3,000 for a completed hull, ish. still have a lot of questions to answer though.
Don't sell yourself short. I get the concerns very much, hell I currently have three unfinished boats and I just started another one not to mention the four vehicles in various stages of restoration. I am VERY ADHD and have a hard time staying on task. If I take even a single day off from a project there is a chance that I don't start back on it, but rather bounce to something else.

With that said, I think one big mistake you're making mentally is looking at it as a "home built boat". You are mentally implying that it will be inferior somehow to a store bought boat and so you feel bad about spending money doing it right. A better way to look at it is a "custom built" boat, one that is carefully hand crafted to exacting specifications using premium materials and stringent quality control. Once you can wrap your head around that way of thinking then you will have a much better time with the project and not look as closely at the price of each component. That may be harder on the wallet, but it will be better on the finished product and may even keep you focused longer to the point where you actually finish something you started (not a slam at all, like I said before: I'm the same)

Please don't take this post as negative criticism, just an offering of advice from someone who suffers the same snags in building that you do and is working to overcome the same.
Previous builds: FL14, NC16, and others...

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Re: Alternate build methods?? long winded post, you've been warned

Post by gstanfield »

Forum glitch apparently, double post.
Last edited by gstanfield on Fri Oct 30, 2020 6:21 pm, edited 1 time in total.
Previous builds: FL14, NC16, and others...

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Re: Alternate build methods?? long winded post, you've been warned

Post by fallguy1000 »

Chenier wrote: Fri Oct 30, 2020 4:16 pm
Lakesurfer wrote: Fri Oct 30, 2020 10:05 am 4. Im not concerned with the overall weight of the boat.
That's like not being concerned with the overall weight of an airplane. Boats operate in a different medium, but weight and balance are still important in the design. When you get the PH15 planing, it's essentially "flying" on the surface of the water. Just like an airplane, extra weight in the hull is going to mean either less usefull load or more power (bigger engine) to get the same performance. TAANSTAFL.
Yeah. The smaller the vessel, the more weight dependent as well. A pound on a 3000 pound boat is not as big a factor as a pound on a 200 pound boat. When you consider a 200 pound man or 3 of them; a 400 pound hull at 15 feet long becomes very weight dependent.

Have you ever been in a 14-16' fishing boat with a trolling motor on the bow? If one guy alone gets forward on a casting the deck; it starts to feel like you are driving a bobber. This forces the helmsman aft and is why trolling motors have 20 foot long cords. If two guys are on the boat; the heavier guy goes aft.
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rick berrey
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Re: Alternate build methods?? long winded post, you've been warned

Post by rick berrey »

I will start by saying you should stay within the designed materials . In concrete form work we sometimes used 1/8" to 1'1/4" plywood for forms , the spacing of the vertical and horizontal support ( stringers and bulkheads in your case ) were dictated by hydraulic,s and material strength . So in theory you could build a male form using 1/8 " masonite and then use solid glass with added stringers / bulkheads for your build . But you would have to re-figure the math for the material conversion . No matter what material you use it has to provide the same strength , and while you may meet the strength requirement,s with a given material , you may also suffer a fatal weight gain which results in a boat that wont float .

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