High Performance MPX Foil/Self-righting Trimaran-The Test Model

MPX Test Model

This shows the hull filled with Super Fill* epoxy. I'ts very light and caused me a big problem in doing the job. I had a batten cut that would "ride" along the center of the bottom and on each chine(which are perfectly fair)-it would have worked perfectly with epoxy/cabosil which would be twice as heavy as this stuff but would have been able to be applied using the batten which would have resulted(theoretically) in a perfect fill. But the Super Fill wouldn't work with the batten-it sort of pulled apart due-apparently- to its consistency. So I had to quickly change gears and apply the stuff relatively thickly using a plastic spreader as carefully as I could to keep a relatively even thickness-no batten. More sanding but will result in a thin ,very light weight job. This filler sands very easily-probably an hour to get thru with 80.
Go to post 1177 for what lead up to this.
* from Aircraft Spruce and Specialty Co.-they have a great catalog!

 

MPX Test Model

Finished filling the deck. This stuff takes 12 hours to be ready to sand so it will be sanded Monday. Had to be applied by hand so that it would be thick enough to be sanded w/o going thru to the carbon.(no batten or plastic spreader)

 

MPX Test Model

I'm taking the rig to my sailmaker in the morning so I stuck it in the car this afternoon. I had previously measured the car for the mast length and it was fine(unbelievably), but the damn thing wouldn't go in with the sail attached to the gaff and boom. I had to take the clew and peak loose and roll the sail around the mast and it went in. Assembly of this boat every time I go sailing will be a bit of a pain-maybe someday I'll get a box and small trailer to eliminate that.
The jib will have the square head cut down and the clew raised up a bit. The main will have a second grommet above the one on the clew now so that I can adjust the attachment point of the clew when I add rake.

 

MPX Test Model

Here are the sails after the mods today-the jib clew was raised and two grommets-one above the other were added. I added the top grommet in case the clew still has to be raised. Two grommets were added to the main clew with the idea that the lower one would be used for certain conditions and the upper one for different conditions. The cutout allows the lower part of the main foot to be rolled up and retained by velcro.
No sanding today, unfortunately.
click--

 

MPX Test Model

Finished the 80 grit sanding this morning. Some filling required then 220,320,400 tomorrow. Then paint.Then rig fitting #2. Then float test #3.Then radio.Then sailing.
Pictures show comparison between filled(center,top; right, below) and sanded hull and deck(left picture). Picture on upper far right, shows the sharp intersection at the bottom and transom:
click for best view--

 

So sailing on Tuesday?

 

MPX Test Model

I'll sail when she's done-and I guarantee that will happen on a Tuesday, Wednesday, Thursday, Friday, Saturday ,Sunday and /or Monday!
or so.....

 

LOL. Along the same lines....

Q - When are you going to finish that boat?

A - Tuesday.

Q - Next Tuesday?

A - Nope, but it'll be a Tuesday.

 

MPX Test Model

Bottom job complete-ready for paint. This is not my ideal level of finish(80 thru 400)-not quite as good as it was originally but ok for now. Her Majesty is becoming impatient-she wants to fly- so we gotta get moving. Paint tomorrow, 3rd float test Friday morning.
The mods were made in three days(27th-30th) and the finish ends today. The finish actually took 4 days(incl tomorrow) with the rest for Real Life. So the actual time "lost" to these mods was 8 days. Well worth it.

 

MPX Test Model

I taped up the boat tonight so that it's ready for paint:
click--

 

MPX Test Model

The modified hull has been painted. It will be further "decorated" someday with vinyl tape and stickers especially to fix paint lines that were screwed up by the cheap masking I used. But right now it is done --with a float test in the morning and rig fitting shortly.

 

MPX Test Model-Final Pre-Sailing Float Test

The results of this test are just outstanding. I wrestled a lot with this -whether to do it or not-but I'm so glad I did. Significantly lower drag hull that floats perfectly!
I put a line on the boat so I could let it drift out with the strong east wind. My idea-other than pictures- was to pull hard on the line to see if I could note any lift from the ama foils-particularly the one on the port side, which was fully immersed due to the slight list(4lb ballast too far to port side). My estimate was a maximum of 4' per second(2.7mph/ 2.3 knots). At first, I noticed, maybe, a slight lift but it may have been due to the angle the boat was pulled-too much up.Tried pulling parallel to the water and there was a slight but noticeable lift on the port foil. Ideally, for pull testing, the pull should be on a mast or mast stump at the CE. One things for sure: I'll have to adjust the angle of incidence of the ama foils by at least one degree higher since the boat no longer sits with the pitch up it did on the last float test(see Summary above).
So now to finish up........
Note: some of the pictures have a blurry spot that I didn't discover until I got back to the shop(condo). Apparently, I put my damn finger on the lens-first time for that!

 

Now that is better than a good day at the office!

 

MPX Test Model

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Yeah-made my day!

 

DL,
Have you considered a R/C glider winch to make controlled speed trials after letting it drift out?
You could dial up your velocity, film records can be invaluable.