JEM Watercraft

Hey all, been browsing the site the last week or so. Found it while doing a search on home made rudders, saw a pic of the sabalo rigged for fishing and bought the plans. Done a decent amount of woodworking but first boat. Looks addictive. A few questions while waiting on them. 1st I will probably be using the lowes 5.2 mm plywood. However I can get the 4 mm marine ply locally for 53 a sheet. Is it worth just cutting the hull out of that and doing the rest w/ the lowes stuff? Also if I go ahead and do the cheap wood I am thinking of glassing the entire hull, assuming this will help strength out. For those who have done it how much did you use and what width? Would you still tape the joints? If not any idea on how much less tape to order? Sorry for all the questions, im sure the plans go into detail but I may be in ft. pierce in the next few days and figured I would stop by Raka and pick some stuff up. Also what width tape would you use? Thanks again.

Making the hull from quality ply is a good idea. But wait until you see the plans until you buy any wood.

You could just tape the seams but it's a multi seam hull. By the time you're done applying the tape, feathering the edges, and making everything smooth, you could have gotten done at once with cloth and save a bunch of time.

I just coughed up $49 per sheet today for 4 mm okuome for my Sabalo build. I have large scraps of ply and particle board that I may make templates out of and then place on the expensive stuff and trace. I figure that way I can put the pieces closer together on the good plywood than what the plans call for. Cardboard would probably work as well. I am hoping to get away with only having to use four sheets this way. I have some smaller pieces of 5.2mm Philipine Mahogany that I could use for frames if necessary.

The reason I went with the marine ply is that okoume is much lighter (13 pounds/4mm 4X8 sheet) than the luaun/meranti/whatever else you want to call it that you get at Lowes, or in the form of merranti marine ply (19lbs/4mm 4x8 sheet). I want a light boat. If I went with the 5.2 mm vs the 4 mm I was already handicapping myself with an almost an additional 25 percent in wood weight. Also the 19 lbs is 46 %heavier than the 13 lbs. okoume. Since the wood is approximately 80 percent of the weight of a wood/fiberglass boat (according to something I read somewhere) I figured the best way to knock off weight was by using higher quality lighter wood. Also, I won't have to worry about voids, and there will be less chance of accidentally sanding through the face veneer like on the Lowes plywood. My experience is that the face veneer is very thin and I have seen it de-laminate when cutting it. But that may have been due to a void in the core. I don't want to take the chance. I will be traveling a ways offshore in cold ocean water. I figure the extra money is cheap life insurance. If I were paddling only in the summertime in lakes and rivers, I would consider cheaper ply. However, the river water temps here were in the high thirties the other day when some people I knew went sturgeon fishing. That was another reason I chose the expensive stuff. Even though I would wear a drysuit in those conditions, it still would be a long cold swim to shore.

I was going to buy 3mm for $35 a sheet that I saw last week, but they sold out and discontinued it this week. I shouldn't have procrastinated I guess.

Ah well, I get my MarinEpoxy and cloth from Duckworth's. I have built a couple of boats with their products and rate it far superior to West System. I have never had a problem with ammine blush with this epoxy. With the West System epoxy, it was like a wax coating on the boat every time I put a coat on. Plus the savings on the epoxy price more than makes up for the additional cost in plywood. Matt has Duckworth's page in the links section.

But then again, I may be over thinking the whole thing and wasting time and money.

Ok cloth it is. It said tape on the materials list is why I asked. I will delay going to RAKA till I get the plans. If i decide to go with the 4 mm for the hull how many sheets would that take? More concerned about it delaminating than the weight. All my paddling is in the intercostal waterway here on the treasure coast. No real interest in going out in the ocean in it. I like snook trout and redfish =)

The hull takes two sheets.

Thank you. I know this topic of plywood has been beaten to death here and I actually read through most of the question and answers on here about it before I asked. What I have gathered is the luan (sp?) is acceptable but may check and possibly delam plus weighs more. Is that about right?

You are pretty much right on. As for Luan sp, the name lauan comes from trees found in the Philippines but has become a generic term in the US for imported tropical plywood. Its also known as lauan, meranti, or serai.

A lot of people on here have encapsulated their boats in epoxy and fiberglass and have had beautiful and highly functional results with lauan. Several swear by it. I have not heard of complaints of it checking, but like marine fir lumber, if it is encapsulated in fiberglass and epoxy, the checking, if any would probably not show.

However, the lauan that I am familiar with in the Pacific Northwest could barely be called a plywood. It is more of a thick core of an unspecified cheap lumber with two thin lauan veneers.

The real problem, IMHO, is that the grain of the thick ply in the middle runs perpendicular to the waterline. Essentially, you end up with a boat made up of almost entirely short grain material. Only the thin surface veneers are running along the length of the boat. This would be very weak. However, If you are planning to fiberglass both inside and out, that would negate this weakness and you may not have any problems.

One thing you could try if you have a scrap of lauan, is flex a narrow piece and then plane off the surface veneer. Check if there are small cracks in the thick interior core ply. This could be a problem if it were used in a boat without complete encapsulation with fiberglass and epoxy. If water penetrated the thin veneer, it would pass right through the the cracks to the interior of the boat.

Luan is a very nice looking wood. I think it looks nicer than Okoume. Why is it so cheap than? Because the core is made of very cheap wood with not much quality control. The same wood is also utilized in marine plywood (referred to as meranti). When it is, the price jumps to $46/ sheet where I live. This is due to it having thicker outer plys with core being made of a higher quality material.

The way I look at it is that you are going to spend many, many hours completing a beautiful boat either way. In the the total cost of the construction, with epoxy, fiberglass, and other rigging, the overall difference in the cost of the plywood isn't a huge percentage increase in the total cost of the boat.

I also considered doing what you are doing and use the good stuff for the hull and the other stuff for the rest. Any problems with the exterior of the hull would be visible to me and easily repaired. However, its the nooks and crannies inside that may start to deteriorate that I can't see that worry me more. Therefore, I will try to use the marine ply throughout. If I was in Florida where the water is warmer, not concerned two much about a slightly heavier boat, and not going off shore too far, I would probably use the cheaper stuff and fiberglass all parts inside and out. However, only if i could find voidless cheap stuff that looked nice.

I should have warned you first that I am overly cautious and if $80-100 more in cost even has the slightest chance of keeping me alive or safe, its worth it to me. I like to think I'm worth at least that much. Interestingly, my wife wants me to make it out of particle board with only taped seams. I don't understand why.

Also, as I stated before, I want a light boat. Therefore, for me the weight savings is well worth the extra money. If I could afford balsa plywood, I would consider it.

Another thing before the pro- lauan folks state their case. I am not against people using the more inexpensive ply. I built a 12 foot jon boat that I intended for duck and goose hunting and fishing lakes where electric motors were only allowed. I bought the cheapest 1/4 inch exterior fir plywood Home Depot had. One face had voids filled with putty and the ones they missed i filled with wood putty myself. I fiberglassed inside and out with 6 oz cloth and painted it with Krylon camouflage spray paints. I built it in 2003. It has sat outside uncovered ever since and it rains here constantly in the winter. Once, it filled half ways up with water which sat in it for a long time. I have not noticed any deterioration whatsoever in the boat.

Thanks for the detailed reply craig(?) I am leaning toward cheaper ply this time simply cause I am young. Which means poor and strong =) So 200 dollars is more important than 10-20 pounds. Its the safety I was debating. lol @ the particle board comment. Since I started asking questions, when do you stain your wood? I am assuming right after it has been cut out for an even finish. Is this correct?

I have been keeping my mouth shut here ,but I need to say a couple things,
BE CAREFUL STAINING WOOD The only problem I have ever had with my boats was from staining.
So make sure you use water base stain and very light.
I have built a lot of boats from laun and it is safe, pretty, inexpensive and I will go anywhere I want with it.
The wood I like best is the 4 mm and between a 3 mm and 4mm built boat to get the same toughness they are nearly identical in weight. With the Marine ply on a 15 ft boat maybe five lbs difference, you just use parts of these sheets not the whole sheet.
Marine ply is great but laun can be used very satisfactory.
Personally I will never use 3 mm again ,hated it,
Saying all this I should add I do not baby my boats, they pulled up banks, run up on sandbars and gravel bars ,even nosed up on concrete ramps, and going down these rivers slammed rocks so hard that it would nearly throw you out of the boat. A lot of this kind of abuse is while the boat has up to 250 lbs of gear and my 225 in it.
These boats are not fragile the way I build them .
Ron
These are my personal opinions and venture there at your own risk