absolute beginner ply/epoxy or ply/glass

i have a couple of questoins really, firstly i am wondering wether to build a ply epoxy hull or a ply core firbreglass hull and am wondering if anyone could offer me any advice on the pros and cons of the two methods? Also i would like to know if there is a better tool than a jigsaw for cutting ply as the jigsaw tends to rip the veneer on the edges up a bit?
Any help you can give me would be greatly appreciated as i am completely new to this i bought my first boat a few months ago and ever since then have been dying to build something, preferably something that floats

 

I would say that it depends on the design of the boat. Some boats are designed with plywood as the center of a fiberglass/epoxy sandwich and the strength of the boat depends on that. Other boats are just made of wood with a layer of epoxy painted on to seal the wood from water. In the first example your building more of a composite boat, whereas in the second your building a wood boat. Personally, I think a composite boat is the way to go. Why not take advantage of the advancements in resin and fiberglass?

What you build depends on what you prefer. Just do some research, like you are here, and you will have enough information to make an informed decision. Best of luck.

Joel
Boatbuildercentral.com

 

If you're worried about your jigsaw cutting too rough, get a finer tooth blade for it. The finer the teeth the cleaner the cut.

 

thankyou

thank you

 

A cored construction requires that the 'glass work be first class and is the structural component of the craft. The plywood serves to hold the skins apart (inner and outer 'glass skins) and this is what makes the structure so strong. This method requires much more skill, experience and effort working with 'glass and related products. You'll spend 80% of you time sanding, because of the shear amount of 'glassing required.

Sheet goods (plywood) construction uses a different set of principles and techniques to make a strong boat. There's more then one technique, but most ask for a light skinning with cloth set in epoxy. Not epoxy alone as this serves little propose unless it's CPES which will receive it's own treatment. The cloth or other reinforcement in the epoxy matrix provides the abrasion resistance that can't be gotten with a few coats of epoxy alone. These designs also rely on epoxy used as a glue and joint strengthening material (fillets and taped seams) Coating a hull with epoxy alone amounts to little more then really expensive, brittle paint that can't be left to it own as it has no UV protection. Soon as the panel flexes from use the hard epoxy coating without reinforcement will crack.

Plywood construction, be it stitch and glue, tape and seam, frame and conically developed panels, stringer, batten seam, lap strake or other are truer wooden construction techniques and require better wood working skills. The sins of wood butchering, covered over with layers of 'glass in cored construction can't be as easily hidden with these more traditional wooden construction methods. In my mind it's faster to build in the more traditional methods, because of the labor involved in sanding and finishing 'glass. Other then popping a 'glass boat out of a mold, where the prep produces a near flawless finish, the one off construction methods with cored construction, require a large percentage of construction time devoted to sanding 'glass (not many folks favorite thing to do) and doing this well requires lots of practice.

 

As far as ripping the veneer when you cut , try a finer tooth blade , I would also trade in the old jig saw for a newer design if you can afford it. I like a variable speed orbital jig saw the shaft works in a circular motion and it does'nt hog out like a straight shaft
up and down motion does and I always use masking tape on thin wood ,or Plastic products. Your tooth direction is most likely in the down direction so the side your cutting should be the side you see ( outside) This will minimize the slivering.

good luck
donjames

 

Bosch and probably other companys offer a blade that cuts on the down stroke wich will at least leave the line side very clean, also go slow the slower you feed the tool the cleaner the cut. Last don't forget about the saws that don't plug in, regardless of how great your power tool collection is it is all but impossible to turn out good work without good old fashioned hand tools.

 

There are a number of techniques you can use to prevent that type of rip out. One is to score the work, before you cut, another is to sandwich the work with a sacrificial piece of something on the side that will rip or both sides.

Good tools with sharp blades and techniques will carry you through. Typically it's caused by too aggressive a blade, be it speed or tooth count. Sneak up on it and fine tune the edge with a tool less likely to do as much damage. Personally, if I think there will be rip out, I'll sandwich it between some scrap stock.

 

I use a router with a cutting bit, the kind used in roto zips. Very clean cuts.1/8in wide.

 

I feel that the best building methode for an absolute beginner is the strip-planking methode.
You set up a frame with your keel and some tranverses/bulkheads. Start attaching these strips of wood, and at the end apply one layer of glass to seal it inside and out.

Check this out:

http://www.selway-fisher.com/Stripplank.htm