Small trimarans under 20'

Looks like it was fun. I like the tri very much-great job.

 

I am liking the look of the
new Astus 20.5 very much. for me, this is hitting a very hard to achieve sweet spot rather well.

Astus 20.5 http://www.astusboats.com/astus-20-5-100.html

 

I just started reading the thread. Through about 10 of 60 pages so far. I have seen no mention of Frank Smoot's Slingshot 16 or Slingshot 19. Found no mention in this thread with various searches. Opinions on those tris? Main hull seems similar to Mike Waters' W17. I wonder about his preference for small and simple sails. Makes me wonder if his 14mph claim is conservative. And he uses waterproof fir ply, mostly 6mm, so I think think it could be made lighter. Cheap though ... a priority for him.

www.diy-tris.com
www.woodenboat.com/boat-plans-kits/slingshot-19

As to Doug's obsession with foils: What about weedy inland waters? Where I sail our kickup rudders and centerboards are necessary to shed weeds regularly. The weed issue is one attraction of Smoot's use of leeboards.

 

If you like a priori the new Astus 20,5 , you can have a taste of it from its little brother Astus 16,5 (also a VPLP design, and a great commercial success) through the numerous YouTube videos posted by TomKirkman1 like this one :

 

Skeezix,

I've been following Smoots designing / building for quite some time.
His hulls are very simplified in shape.
The thickness of ply is pretty small.
Lots of details seem to be aimed at keeping the speed down, so the structure doesn't get too heavy or complicated.

Personally the sail area has always been much too low for me to get interested. But thinking about putting more area up makes me believe the structure would not be adequate.
What I'd like is a Hobie 16 area on the Slingshot 16. That's around 230 sq ft.

The price seems to be right, though.

 

I purchased plans for the Slingshot 19 and I am considering building it as the folding version. I am no designer, but I have played with some numbers from his dimensions and materials and I think it can take a lot more sail and a higher CE. Especially the folding version where the akas are encased for part of their length and there are stringers for shrouds and possible tramps. I sketched up a 180 ft2 high aspect sail plan, an admittedly oddball standing gunter, to use spars I have on hand. The mast is teardrop profile about 3.5" x 2.4" that I will rotate on a ball and socket. I think that the gunter top will twist off to spill gusts better, and the rotating mast will make sure the gunter doesn't twist too far. Bad thing is that a SailRite quote of about $800 quickly counters the Smoot budget. Before starting, I also am taking a serious look at Mike Waters' W17 and Richard Woods' Strikes for improvements in hull plans, especially amas. I think Mike's ama theory makes sense. I like Richard's folding design a lot. I really appreciate some of the theory particulars Richard has offered earlier in this thread. (I am through page 20 now.) But the two appealing aspects of Frank's plans are the pedal steering and the leeboards for use in the shallow weedy lakes I sail. So maybe I will buy plans for the other Tris too, and create an amalgam. Yes, that is risky, plus adds plan costs. But I don't mind supporting designers. And the worst that can happen is I build and sail a suboptimal tri, and maybe take a swim amongst the wreckage. I will have built and sailed a tri!

 

TMS 20 High Performance Trimaran: this boat should be included here. The original thread : New Design TMS-20 Racing Trimaran https://www.boatdesign.net/threads/new-design-tms-20-racing-trimaran.29519/

Quote from the thread:
"I started posting on this forum so I thought I'd start a thread on my new boat the TMS-20. This is very high performance trimaran developed by Kurt Hughes for the Worrell 1000 race. The idea was to give the crew a more comfortable ride than the usual perch hiked out on the high side of a beach cat. The very wide overall beam gives it a nearly equal righting moment to the cat. Unlike on the cat, the crew can be rested and focused during the long, wet race. "
LOA 20’0”
LOW 19-9”
Beam 17’
Draft 10” / 2’3”
Weight 497lbs
Displacement 906lbs
Main 147sq’
Jib 47sq’
Spin 161sq’
Total up wind 194sq’

 

I have purchased W17 plans. Conferred quite a bit with Mike Waters and I see a number of advantages of his W17 over Smoot's S19. I like the idea of longitudinal seating in a skinny shell for just 1 or 2 in a boat that really scoots. But I think that it would need to be a foiler for that, and foiling is a level of complexity I don't want to attempt, and poses problems for weedbound Midwestern sailing.

So that sail experiment I sketched above is likely out too, because Mike offers attractive wingmast plans.

 

I'm just curious about your lake- is it very shallow with weeds growing up to the surface? Wouldn't that be a problem for a daggerboard or rudder?
Good luck with your W17!

 

Shallow indeed. It is the pool above the Mississippi dam at LaCrosse Wisconsin. These photos should make it clear. Swing up rudder is pretty much required. Swing up centerboard preferred, so I will need to think carefully about W17 swinging dagger hybrid. The weeds are why I thought the S19 leeboard would help. In any case, a tri that does well upwind like the W17 should help. (See Mike's comments on his hull and ama design of the W17, quite promising.)

 

I planned to do my first test.sail after one year of re-build on my small trimaran Chryz10 Outlaw.
Weather was super, all was ready. But... forgot my beam at home and some other things. Will try soon again
My sawing and trampolin seems to fit well.



Chris
www.chryz10.com

 

Cholsson, just curious: how does the total buoyancy of your main hull compare with the total buoyancy of each ama?

 

I dont understand exatly what you mean but the buoyancy is something like 25%-50%-25% for the hull. Will try to sail on tuesday and film some then.

 

Thanks. Good luck on Tuesday!
PS-I could have phrased the question better-sorry. We know that the mainhull supports 100% of the boat +crew weight. I was curious what percentage of the total weight would be supported by a fully immersed ama?

 

Looks like the main and outrigger hulls were taken from the same mould so the crew will be perched way out to windward for stability and power (unlike your fantasy centre hull seating arrangement)?