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

Sweet looking hull, Doug.

 

High Performance Self-Righting Trimaran: The Test Model

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Thanks, Gary!

 

High Performance Self-Righting Trimaran: The Test Model

This is a good reference to use to compare actual weights with predicted weights. Just before float test model main hull weighed 3.4lb.

See bottom of previous page for more float pictures and details of the float tests.

 

Interesting project doug, it reminds me of an early frank batherwait ( sorry about the spelling ) project, aside from your arma configeration. I look forward to seeing this model sail

 

High Performance Self-Righting Trimaran: The Test Model

Thanks! This boat is similar to a 20' tri I built in the '70's that didn't use foils like this boat will on the main hull and ama's. But it had a planing main hull as this does. This boat is much more highly powered and wider than that was and may be self-righting. It's going to be fun to find out what works and what doesn't.....


My 20 tri from about 1971-click on image:

 

High Performance Self-Righting Trimaran: The Test Model

The next episode(Part 1) will be the building of the two amas(version 1, low buoyancy, wave piercing planing hulls ) These hulls are designed to NOT contact the water except intermittently. The design question is what about getting started and gusts when tacking. The answer, I think, is based on my experience with my previous trimarans but mainly based on my experience with the F3 that had a very low buoyancy ama with a foil on it. Same as this one except the foil configuration is a bit different(curved lifting foil on the ama and T-foils on the main hull daggerboard and rudder). So if the F3 experience holds true there will be just enough buoyancy to allow the speed to build and the foils to take over. That's part of the reason for the oversquare configuration. The version 1 amas will not be able to support the sailing weight of the boat when it is not moving.
The amas will be connected to the boat by a "device" I'm calling "the curved piece". For some reason my imagination fails me with this critical piece in terms of what to call it. Anyway, the curved piece has just about the same buoyancy as does the version 1 ama for added resistance to gusts knocking the boat over. But the total buoyancy of the curved piece and the ama is less that the all up sailing weight of the boat. It's done that way on this particular boat to help insure its self-righting capability and resistance to capsize in the first place. If the buoyancy of the ama/curved piece was enough to lift the whole boat that would facilitate
turning turtle especially with the oversquare configuration.


Pictures,L to R: F3 RC foiler, MPX-12 ama+ curved piece-similar to curved piece on SRT.

 

High Performance Self-Righting Trimaran: The Test Model

The next episode(Part 2) will include a number of major and minor details-some of which will be deferred until after static capsize and pitchpole tests:

1) Building of ama curved foil and matching trunk. To be built so that same micro-mold works for both sides. One off mods to trunks to include facility to adjust angle of incidence of the lifting portion of the curved foil by moving top of foil fore and aft. Toe in of foil will be adjustable by moving front of trunk.
2) One off building of daggerboard/mainfoil/ballast bulb as a single unit.
3) Building rudder and rudder foil as one offs.
4) Adding gantry to main hull in a manner such that it is adjustable in distance aft of transom. Will use same design as MPX-12(see below). Rudder will fit in cassette that is pivotably attached to circular component of gantry. Cassette will facilitate adjustment of the angle of incidence of the rudder hydrofoil.
5) Building and installation of daggerboard trunk such that angle of incidence of main foil can be adjusted by moving top of daggerboard fore and aft.
6) Installation of mount for dual wands for altitude control system for main foil.
7) Final design and installation of forestay mount/ Hoyt jib boom OR integral mast mounted system OR athwartship sliding mount for for jib boom pivot.
8) Building of "nesting" radio box that will fit between the two crossarms in the center of the boat. The radio box will contain the receiver, mainsheet winch, jib sheet winch and rudder servo. Angle of incidence adjustment of main foil and curved foils will be able to be included. Battery will be clipped on to box in such a way that it is easily changed.
9) assembly of crossarms to curved pieces supporting amas and structural carbonation of crossarms to vertical tubes in main hull such that the cross arm can be installed by pushing the assembly onto the vertical tubes. The assembly will be easily removed to facilitate transportation of this very wide model. Assembly will also allow slight independent movement of forward and/or aft cross arms to change the ride angle of the planing ama(set at +4 degrees).
10) Sails made by "Sails by Morgan"(Scott Morgan) and rig built.
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Pictures, gantry out and in on MPX-12-same design on SRT.

 

High Performance Self-Righting Trimaran: The Test Model

A couple of shots of the one off #1 ama partially complete:

click on image--

 

Looks good doug!

 

High Performance Self-Righting Trimaran: The Test Model

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Thanks!

 

High Performance Self-Righting Trimaran: The Test Model

This is ama one roughed in. Much more shaping to be done. Using this technique is easier for me than hand shaping styro and it will be(should be) lighter. The hull has no stringers and only one(removable bulkhead). Again, this ama is designed for intermittent immersion at displacement and planing speeds. She will "pretty up" (to some extent) in a hurry when I do the final shaping.

click on image--

 

High Performance Self-Righting Trimaran: The Test Model

Ama two roughed in. Shaping and carbonation is next. Too much rain today but the water sure looks good when its stormy.

click on image:

 

High Performance Self-Righting Trimaran: The Test Model

Amas ready to carbonate. Real good news:
1) Ama "A"- .27lb
2) Ama "B"- .29lb
Target is .625lb per ama-I'm going to make it!(see post with model targets above)

Pictures: L to R, 1 & 2-ama art:1-bottoms to center, 2-decks to center, 3-view of bottom, 4-view of ama showing planing bottom "extension"(not really an extension) with the double ended hull. The flat spot on the aft 8" of the deck(top in picture) is where the "curved piece" is mounted, 5-another similar view, 6- ama back end viewed from above, 7-MXP-12 showing relationship of "curved piece" to ama on a smaller tri-"Curved piece" ties in ama to cross arms. Purpose is to increase back up buoyancy and raise cross arms higher above the water to reduce wave impacts. Both the SRT ama(version 1) and the MPX-12 ama(version 1) are planing amas: the difference lies in the fact that the MPX-12 ama is designed to be sailed on as speed increase until it supports the total boats weight(with help from the main hull foils in managing ride angle) and the SRT amas are NOT designed to be sailed on-they are designed for static buoyancy and intermittent contact while underway.
for best view ,click on image:

 

High Performance Self-Righting Trimaran: The Test Model-Ama

Both amas carbonized and coated with epox+q-cells. Unfortunately, I had to go out and missed the trim window so I've got a little bit of highly nasty grinding to do. Also, didn't have peel ply so I had to sand the hulls before q-cells.

 

High Performance Self-Righting Trimaran: The Test Model

All together for the first time-well, sorta. They are close to their relative positions(except athwartship where the amas will be at the end of the crossarms). The angles of everything are not obvious so:
1) the crossarms will be cut at the center and pivoted forward and up
2) only the forward 8" of the "curved piece"(not shown-but fits between the outboard ends of the cross arms) will be in contact with the aft 8" of the ama
3) the dihedral angle of the cross arms will be fairly high so that the amas are well clear of the water at static main hull displacement,
4) the amas plus crossarms will be one piece and easily lifted off the main hull for transport of the model.

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Thank you, Dennis!
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