Pine Ply + Epoxy 4 questions for the price of one

1 - Hi my question is simple i see that lots of ppl recomend oak or okoume Plywood for hull building . That makes me wonder would it be possible to build out of Pine plywood (regular cheep plywood) & also would MDF be a good ply construction material for the hull?

2 - Also how would those material fair vs other material ? (any known issues here ?)


hull would be coated on both sides with a layer of Fiberglass & epoxy.

3 - how thick is the wood used in ply construction for the hull & the bulkheads ?

4 - would it be possible tu use a similar technique of origamy /Kss with plywood ? (lay the hull material flat then make grooves then fold in place then fill with epoxy the "cracks" of the inner hull)

 

Who is recommending oak plywood?
It isn't the pine ply per se, but the way the plywood is made that matters, so usually fir is used rather than pine since it's about the same cost but is a bit stronger for its weight.
Glue and number of layers and lack of inner voids coupled with a reasonably inexpensive, light and strong wood make for a good plywood.
Whay say hull will be coated inside with glass and epoxy? The inside needn't be glassed if built stitch and glue. It's best to wait until you have more information before you specify anything.
Cutting grooves is a waste of materials. The whole idea of using plywood is to get a benefit from its inherent strength. If all you want is a means to seperate the inner and outer layers of glass, use foam. It will be as strong as grooved ply, which I would never do.
Start with a design you like based on your actual needs and then stick closely to the plans. Any questions should involve minor details. It takes a long time to get to where you would design your own construction technique or even your own bulkhead thickness, which would of course vary from boat to boat.

Alan

 

To anwnser your questions

grooves: http://www.kelsall.com/methods3.html has a technique where they lay the hull material flat prep it then shape it by using a kind of frame i was wondering if this technique would be usable with wood since wood dosent flex as much as foam & plastics (it tend to break or crack rather then shape) i would make grooves to allow for flexing (if the wood is made thin at a specific point it will permit shaping ) i have attached a picture to show better my point for this


Oak ? well im not shure but okoume was defenitly recomended in a few places

i would go with a cheaper wood if i can as i wont be using wood as a visual feature but rather for streght

also i specified the fiberglass part as a detail to mention i wont leave the wood bare or indicate whatever clue i can provide
eidt: also i would fiberglass only to amiliorate the durability & "sheild" the wood against water as im shure evetualy some might end up in the bottom of the hull [be prep for the worst hope for the best is the saying no ?]

thanks for your reply btw

 

Eric, you're confusing or possibly attempting to mix different engineering principles and construction methods across planking materials with dramatically different physical properties.

In a nut shell, plywood is a self supporting, rigid panel that requires little additional reinforcement to provide inherent stiffness. The grooved foam or other "core" type materials aren't self supporting, have little to no stiffness as a stand a lone product and must be used in a sandwich structure, which employs a different set of engineering principles, to provide the completed "cored" panel it's stiffness, typically requiring einforcement sheathings.

The two different concepts aren't interchangeable.

Without a firm grasp on the engineering concepts and principles, plus a careful understanding of the physical properties of the different materials used, development of a new system or substitution of material types in a current building system, is wholly unwise to say the least.

An example of this is a good look at the choice of MDF as a planking material. Once you know what it's made of, how it's constructed, the materials used and their physical properties, you'd understand way it's not a good choice for a planking material.

 

Always good to ask, Eric. MDF is not ever seen on boats for good reason. It is as good as cardboard when wet.
Do you mind saying what your goal is? If it is to build a boat, that is a very worthy goal.
Plywood is the way to go if you want a good beginner's method that you can take to a very high level or move on to more complicated methods.
Even simple ply designs have been developed over the years to an amazing degree so that at this point only extremely experienced technicians are likely to improve on the state of the art. The rest of us can take it easy because experts have done their job. Those out there who have studied, practiced, and built according to these methods (like PAR, for example) are willing to pass along their knowledge to us for free.
Stick with it here and you won't have to go anywhere else if you want to build your first boat. All you need to do is ask.
What is it you want to do?

Alan

 

pine ply?

Dont waste your time with cheap materials - in the end you dont save much. I used a average marine ply = WBP and epoxy. It ended up the cheapest method because the 9 mm ply is only covered inside with two coats of epoxy (painted on with a short brissle roller) and outside bottom one layer of 600 gm woven glass cloth and then two coats epoxy. The boat is 4m long and 1.2m wide. I use the boat every second weekend. It sleeps one comfortable and two "cosy" - with 5 hp i use 5litres = 1gal approx of petrol a DAY. WOT with a 12 year old it does 12kn. With three adults it comfortably cruises at 4kn.

You cannot imagine how much fun i have had with this boat. It is strong and stable. There is nothing in this universe that will ever be as exiting as sleeping on a boat and having the first cup of coffee at sunrise on the water. Sex lasts 10 min maybe? twice a day? boating lasts a lifetime.

 

Hey Buddie that boat is bloody awful but HEY she gives you pleasure, i like your spirit, have some rep points and go get em, but fer jeepers sakes dont land a 500kg mako in it

 

... and dont waste your time with no professional plans???

For a little bit more you can have five times the fun with your boat .... and maybe have it stable enough to have sex on - 3 times a day !!!

 

ok ok i wont land a big fish in it

I do agree that one should buy a good set of plans if you are going to build a boat that you intend keeping. But you must build something small first then move on. Time management is a bigger problem than material costs -even on a little box. When you start cutting wood in the garage the wife bitches non stop - the neighbours cry about the sound of a drill at 11pm - you always have to cart children around to school **** - the list goes on and on. BE WARNED.

This was a Ply Epoxy experiment for me as i had never worked with epoxy before. Now i can strongly recommend the medium to beginners. It is easy - cost effective and strong. The point i want to get across is that many newbies are looking for cheaper alternatives which is a waste of time - ply - epoxy is as cheap as it gets.

Building my little box el-cheapo has given me 100% confidence to move onto my next 4 year program. So far it looks like this is what it will be 10.6 cat. After the 4 years i will probably be on my own on the boat any way so WTF

 

Ahem : atm im just checking what possibility i have & with what would i build if i build . im pretty new to boating & my experience is verry limited
i entend to follow some courses of sailing to actualy extend this experience
& maybe take litle cruise as i dont even know if i actualy like the thing much & if its worth investing time in this hobby.

the second thing is im nowhere neer buying a house & i dont actualy have land to build so this will be another major factor. if i build a boat im looking to spend quite a lot of time on it even living in it i was looking at a 42-46ft sail-catamaran that can go cruising offshore.

i actualy never left my own contry(canada) so im looking at this for travel also.

i was thinkin i could build a smaller boat (16-20ft) to practice a bit then sell it to make a litle profit to finance the bigger boat. my guess about that is if its fairly sturdy & build with attention to details it will sell well.


sorry for that long post
ps: nice boat & thats exacly my point ... tho for a bigger boat you need a litle more research on the desing . Also my budget is curently = 0$ so

 

No really?

 

hum realy what ?

 

I know what you mean. That looks like a nice little skiff! You have beaten the system, I think!

 

Manie, your boat looks fine. Don't pay attention to the voices behind the curtain. Though it may not be everyone's cup of tea astatically, it works for you and more importantly it's built, blasting around the local waterways, with the pride of accomplishment that only comes from crafting something from your own hands. It feels good doesn't it.

Some build to get out of the wife's hair, enjoying the process. I know a guy that has been building his little dayboat for seven years. It's his "therapy".

Others like me, want to splash the thing (finished or not) and start enjoying our building abilities as soon as we can (often how I precisely determine just where to paint the waterline). For people like this, it's the satisfaction in use, which drives us. It gives us ideas for then next great project.

Good job Manie, have fun and screw 'em if they don't like it, you're out on the water, while they're watching the new fishing show on the toob.

 

Jeez PAR that was rather nice of you - thanks
i frikkin hate TV and i am starting another "boxy"
watch this space