Step by Step Building a hydroplane / MRC is up and running

[Bill Huson]

I would suggest that you not run battens through a planer. Its a little academic because many small shops don't have one.

The feed roller will crimp the top fibers because the pressure is set up for a wide board not to slip. I have seen small battens come out the planer like a banana. The wood aircraft construction rules so state also.

I should clarify - a SURFACE planer, such as my Ryobi AP-10. Feed rollers on that puppy would have a difficult time squishing balsa wood. After running thousands of feet of Sitka, Obeche, pine, fir, cypress, and western red cedar through it I have never had a stringer come out like banana.

[blueskyracer]

So true Bill. Mine is a Ridgid planner and I Have always got nice strait wood. In fact I wish the suckers would grip better at times.

[Dave M]

Agreed

Mike/Bill, we only take 1/32" off at a time per the instructions as well. There is very little pressure on the fibers. It would probably burn it before squashing it.

For the scarf joint, that is standard for marine applications in this class boat. If there were less stringers and cross frames, a different scarf might be a better application. But for the small amount of pounding and strength this style boat will receive, it is more than plenty. West System Epoxy is very strong, don't under estimate the strength of this. If I wwere using plain old wood glue I would certainly adhere to the standards.

[blueskyracer]

Moving on to the next step all plywood has been rough cut or prefitted as in the case of the tunnel plywood and the scarf joint is finished. Now I will coat the areas that will not be accessible after the ply has been installed with a thinned down mixture of epoxy. Then I will roll epoxy on the lower surface of the plywood and brush the stingers and then install the bottom plywood with ring shank nails and stainless steel screws in the transom and motor mount.

[Tim Weber]

Mike,

How do you like the Engleman? It's all we use.

Also, where the tunnell is, why not use a little 1" rabbet plane?
It looks really hard to square that with the sanding block.

Tim

[blueskyracer]

Tim this wood is the best. I am luck to have three family members working at the mill in town and they have a great boss. He gives me such a great deal on the price.I just picked up 10 1"x6"x12' pictured and ordered 20 more 1"x8"x12' for next week. They have no or very few iddy bitty knots and only weigh a little more than pine.

They were all hand picked as they came off the planner

[Bill Huson]

nice lumber!

You might investigate the bendability of the specie. Example: Doug Fir is heavier and stiffer than spruce/pine, but since it is stiffer one can reduce the scantlings for a stringer. Scantling = boat talk for lumber size of parts. `Nother example: instead of 3/4" square you could go with 3/4" x 5/8". 3/4 being the vertical (load direction) measure.

Course my mindset is on building a 15ssH boat that hit the minimum weight of 350# with my 6' 180# body on board. I doubt a boat the size you're building needs to be all that picky about gross tonnage.

Also you mentioned ring shank nails. They are good, I have a pile of bronze ring shanks (salty water here), but when the tool budget allows grab an air stapler. I have a junky cheap one from Wholesale Tools that has spit thousands of staples and is still punching them in. Thing is close to 30 years old and I don't think I can get it apart since it is wrapped in protective coats of WEST resin.

[mdaspit]

Building your own boat and racing it, has to be the coolest thing of all.

[blueskyracer]

Bill I use a stapler up to the point of putting the skins on. Then I use the nails cause I have had some staples start working there way out on the bottom before. Won't happen with the nails

[blueskyracer]

Building your own boat and racing it, has to be the coolest thing of all.

Mark it is kind of like flyfishing, you don't feel like you have done it all till you catch a fish on a fly you tied yourself.

[krazy karl]

Species

Most of it is Engleman Spruce Lodgepole

I am building a Hal Kelly Airborne for recreational purposes. Due to my location clear spruce or pine is really not available to me at a reasonable cost. I have gotten some rough clear poplar from a nearby cabinet shop and thought I would give it a try. It is fairly light, quite strong and seems to bend reasonably well. Has anyone else used this material and what kind of results did you have. I am on to plywood now however. As for scarf joints I am using a hand power planer and getting pretty good results.
kk

[Dave M]

Popular

I am building a Hal Kelly Airborne for recreational purposes. Due to my location clear spruce or pine is really not available to me at a reasonable cost. I have gotten some rough clear poplar from a nearby cabinet shop and thought I would give it a try. It is fairly light, quite strong and seems to bend reasonably well. Has anyone else used this material and what kind of results did you have. I am on to plywood now however. As for scarf joints I am using a hand power planer and getting pretty good results.
kk

The popular will work just fine. I have used it and built three boats using it, that are still out there after 10 + years. The only time it bit me was when I ran into a jam and went to Lowes and bought a couple boards to finish up. I was still new to the game then, and did not realize that the so called dust produced when cutting them was rather stringey and not powderey. (are those words?) Well you guessed it, they were not good and dry boards. Once the boat was finished and ran a few times it started splitting at the seam on an area. The area I used the Lowes wood. I thought the epoxy failed and called them and they tested some from that batch. All good. They asked questiosn and they determined the moisture in the wood expaned the wood and there is no epoxy or glue on this earth that can contain mother nature. When the boat sat out in the sun at the races, it heated up and the mositure had to go some place, even though it was coated in West, etc. So it split the seam. That is the only caution I give on popular. It is slightly heavier than Sitka Spruce, by about 12% if I remember right.

If you are not to concerned with weight, have at it. A lot cheaper than spruce.

[Bill Huson]

poplar

I am building a Hal Kelly Airborne for recreational purposes. Due to my location clear spruce or pine is really not available to me at a reasonable cost. I have gotten some rough clear poplar from a nearby cabinet shop and thought I would give it a try. It is fairly light, quite strong and seems to bend reasonably well. Has anyone else used this material and what kind of results did you have. I am on to plywood now however. As for scarf joints I am using a hand power planer and getting pretty good results.
kk

The purists on the Wooden Boat Forum would pitch a hissy over poplar because it is known to rot rather easy. But we're talking occasionally wet boats stored out of the rain - poplar is just fine. Coat it with resin or several coats of varnish and poplar is super fine. And yes I have used poplar. Nice to work with, no problems at all.

[Mini Max]

You might call the lumber yard and ask for "stair tread" material. Stair tread material here in N.C is clear yellow pine planed to 1 1/4" thick, 12" wide and 12' to 16' long. It is nice and strong though a little heavy and bends well. It costs me $2100/M board ft.

I tried poplar once for plug building but I guess I got some KD material with internal stress and rippings would not stay straight. Never tried it again.

[krazy karl]

Poplar

Thanks for the comments on the poplar. What I am getting is rough lumber that has to be ripped and planed. It comes out really nice, as it cuts and planes very smoothly. I am not really concerned about weight as I will use the boat for a lake racer. May possibly be used in B mod if the class is run again in Region 11, but weight is not an issue as I am fairly light. I have to put 7 or 8 pounds in my heavy a** Zorkin to make minimum in C Mod and 35 in my Sorensen marathon boat to make minimum weight in C Stock. The boat will be completely encapsulated in epoxy.
kk