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

[Mini Max]

Yes I know the plotter is good, but unless you have the toothed wheel to keep the paper registered, especially on long plots it can slip and the paper is also affected by changes in humidity.

You are right, I checked office depot and office max on line for carbon paper, no luck. However, I buy an amazing amount of supplies and tools from Amazon.com, and the carbon transfer paper in rolls looks especially useful if you scroll down the list. It is a pain to line up a row of letter size sheets for long lines and the carbon can be used over and over again.

http://www.amazon.com/s/ref=nb_sb_ss...x=carbon+paper

http://www.amazon.com/s/ref=bl_sr_ki...dtextbin=SARAL

[blueskyracer]

Raymond I put in all the lightening holes the minute I turn the boat over before I put in the deck stringers. But with our boats it is not really necessary since most of the ribs are only 3mm thick. I think this time I will save all the disks and weight them after I drill them out. I would guess they will add up to Maybe a pound!

[Raymond]

I knew I should have just been patient and watched to see how it panned out, however thanks for answering.

[blueskyracer]

Did not get much done this weekend. We had our club meeting and started making our own decals so had to much other stuff going on and just not enough time!!!!

[Dave M]

Bingo

. But with our boats it is not really necessary since most of the ribs are only 3mm thick. I think this time I will save all the disks and weight them after I drill them out. I would guess they will add up to Maybe a pound!

Actually less than that on that size boat. For an 850CCMH it is less than a pound... Not worth the effort, seriously. Wack it some place else.

[form-e one]

i agree with dave also ya want to keep any water in the cockpit so as not to go to the outside sponson,,,also have found out in 850 wieght is NOT really an issue,,,,ha mike any plans in future to sell glss sponsons for your kits??..would save alot of time for people ??..

[blueskyracer]

Here is the latest progress. I have got one sponson framed and glued and the afterplane is all formed up. The othere side has been fitted and is now ready to glue. Note the edge of the sponson is made up of three strips of 1/4 inch laminates with the first one being glued and screwed. The last two strips are strictly glued.

As far as making fiberglass sponsons it will not happen. Main reason being that I remember what happened years ago when Ron Jones came out with the canoes like the ones being used today with the unlimiteds. He sold a set and then that person made a mold off them and it kept snow balling till the originator got nothing. Also would not be cost effective for all the different size boats.

[blueskyracer]

a couple more pictures

[blueskyracer]

This is the last set of pictures in framing up the bottom. Now I have a lot of planning and sanding work. I will post again when I have all the surfaces ready for some plywood. I also have to coat all the frame work that will not be accessible after the plywood is installed.

[Mini Max]

God Bless Gougeon Brothers and epoxy bonded construction. I have a 1934 Jacoby hydroplane and it must have been built with 10,000 tiny brass and bronze fastenings.

It is interesting, I did some three point bending tests on 11 ply 1/2" ply some 35 yrs ago. If the plain plywood sample failed at 1000 lbs, the sample ply with a 6 oz cloth in epoxy on one side only, either top or bottom failed at 2000 lbs. The sample with glass cloth both sides failed at 2700 lbs. A sample that had an unglued butt joint with glass top and bottom also failed at 2600 lbs. The failure mode in plywood starts with the first layer. The glass was better than the wood for that. The bonded structure eliminates punching holes in fiber from fastenings. Toilet paper doesn't have to tear on the perforations but.........

Of course plywood with glass cloth is heavier than ply alone, but not twice as heavy. A Little bit of composite can do alot to help miracle fiber W out in high load areas.

[Bill Huson]

planing stringers . . .

My late friend built a simple tool to shave all the bottom stringers flat. It was a slotted board about 6" wide that ran across the hull had two "runners" attached to the ends which slid along the stringers attached to the inside of the airtrap/sponson. Insert router in slot, dial a flat bit to the correct height, fire up router and successively "plane" all the stringers flat with respect to each other by moving the rig fore and aft and moving the router side to side to line up with each stringer.

Might have been easier to do on my boats since I built the boat off the "sponson frame" which ran the length of the boat and included inside of sponson, little useless but pretty deck fin, and airtraps.

[daveracerdsh]

Planing stringers

Very interesting concept......would you by chance have any pics of it you could post? I don't put a tunnel in the bottom of my D stock boats....with the Tohatsu being restricted to 1/2 below the bottom do not see the need....so I take a very flat board, affix a stiffening board across the top, and staple 36 or 40 grit sandpaper across the width of it....if the bottom is 36 inches, you make the assembly a little wider..and use it like you would use a stink block on the bottom of a runaboat. I try and make the last 24 inches as flat as possible...and this seems to work great. Takes maybe an hour or so to get it perfect, assuming everything is level and square. The boat in pics has an inset transom, So I am betting it is either a pro boat (125) or a CMH/DMH. Just my feeble bet....but it sure looks nice Mike.

[Bill Huson]

Planing stringers

Sorry, no pics. The cross board was MDO with 1x2s screwed to upper edge to brace the deal since you don't want the cross board to bend under the router weight. The slot was large enough to allow the router spindle room to spin, and there was a means to clamp the router in position - I seem to recall a strip of metal (aluminum C-channel?) that spanned the slot on the bottom and a screw or bolt into threaded holes in the router base. Blocks of hardwood on the edge were set to the bottom span so they slid along the outer stringer. The end blocks were adjustable from 34" to 36" wide.

I would set it up, dial in the correct bit height (used a 3/4" flat end planer bit), and clamp the router over a stringer. Gently slide the rig fore and aft over stringer, reset to next stringer, repeat. Although I only cared about flattening the aft several feet of the bottom I usually ran that puppy all the way forward since it was easy-breezy. It was a 50/50 process, half the time used to reset the router position, but overall time was maybe 15-20 minutes to do the whole bottom, and I knocked a few out in under ten when I got used to the rig.

Getting the bottom stringer framing true was rather important for my 155ssH boats since I used 4mm with face grain cross ways (about 30% stiffer) on the bottom, not much wood there for stink stoning.

[Dave M]

Flat Stringers

Would it be just as easy to cut and plane all your stringers at one time prior to installing them ? If you cut all your cross frames, and stringers at once, the heights and widths etc will all be indentical. Then if it is off after installing, it means your level and straight is not correct, or the cross frame holes in the cockpit are not cut out correctly. I found that if you are not using pre-cut from the lumber company, this works well. Get your jig and table level, and then square everything in the jig and double check level. If you plan 3/4 x 3/4 stringers all at once to get final dimensions, it should all be perfect with no additional sanding or planning needed.

But by all means, do it the way you want, that is the fun in building a boat. You tweak the build to suit your style. There is no wrong way to build it, just your way.

[krazy karl]

Stringer Sanding

This is a great thread. I am currently building a Hal Kelly Airborne and am at about the same stage so this is very interesting to me. I use rough lumber that I get from a local cabinet shop. I cut it close to the dimension I want and then plane it the the final size. The bottom is already darn near perfect as to straightness. When I sand the stringers prior to planking(plywood) I use a 2 foot piece of heavy walled 1 1/2" x 2 1"2 steel tubing, has some weight and is straight and very rigid. I glue whatever grit sand paper I want to it using spray adhesive. Sand paper inserts for airfiles work particularly well. This works well for me.
kk