Hobie/J24 Trimaran Conversion

Tube dimensions

Hi Delane, I admire your fortitude. I have been thinking about building a tri for some time along these lines. The idea is not well received in the boating community as I see you can attest to.
I have now acquired a Swiftsure 24, basically built along the same idea as a J24 and indeed designed to compete with J24. I have two hulls from an unknown 17ft cat. I am looking for tubes to connect it all together. What diameter and wall thickness have you used. (I am thinking about using a mast off a bigger boat) I am also interested in the connection detail in your "amas"
I to am planning to modify the hull to have a full length keel, although I am planning on a much narrower keel perhaps 6 inches wide with the rudder in line, the depth will be dependent on where the rudder sits
I have dropped the lead keel already and do not plan to use it.
I am interested to know how your sea trials go with the new hull design.

All the best

Peter

 

I still reckon the YW Diamond is an obvious choice for this style of conversion.
Cheap and already fast.

 

49thDiver,

I'm glad to see others are willing to try mono conversions. Your boat would be a great choice. The beams are 5.5 X 6mm. Each weigh in at about 93lbs. Not sure about the hardness though. They came from carnival tent jack poles and were free!!!

Not sure if a six inch wide keel will do much for you in the way of lift if that's what you had in mind or maybe I mis-understand your meaning.

Ama displacement is important and my 20 ft hull are minimally adequate. With 17 ft Ama's your existing mast may be enough power.

The hull section is completed and I'll post pics soon. Re-launch again today to establish the true water line with everything on board. Will mount the rudder and motor soon and then drop the Ama's 7 to 9 inches.

I'll also take some close up shots of my Ama mounting details as you requested.

 

swiftsure 24

Thanks Delane, I am not looking for high performance or lift.
My design criteria is, a folding, trailer-able, beach-able comfortable pocket cruiser.
The straight full keel is for ease of trailering and beach landings.
The keel will assist with tracking (it may turn slowly but I can live with that) I plan to run the keel most of the way to the bow to allow for
a more vertical stem (bow line), this two will help with reducing spray aft.
A new removable rudder will tie into the new keel.
I plan to use aluminum tube and or box for the arms and hinge components. Water stays seem like a good idea.
At this point mast rigging will remain on main hull.
I am thinking about solar panels and batteries for electric power using a 48 volt golf cart motor (8 to 12hp) with a straight shaft thru a stuffing box in the new keel.


Swiftsure 25 deck view


Side view of swiftsure 24


Hull view keel removed

How did the water test go ?

 

You certainly have your work cut for ya. As for the electric motor, will you be Sailing far away from your home port and what about currents in the area? I think electric motors have a place but not many to mention other than small lakes, sounds and maybe enter-coastal waterways where you max motoring time is no more than 20 minutes or so. A 5HP 4 stroke may be a better choice but I don't know your situation.

I've launched at the dock to check the new waterline and will drop the Ama's soon like next week after our latest Typhoon moves on.

 

Was almost ready to launch and then,,,,,,,,

A few weeks ago we had a really strong Typhoon which took out my boat for the time being. One Ama was destroyed and other damaged quite a bit by the trailer tire when she turned over. Going to build new hulls and get a new mast. Any ideas on good plans for the Ama's?

http://www.youtube.com/watch?v=8GYM-GcogcY&feature=youtu.be

 

Update?

Delane, did you ever get the Vitamin Sea together again? How did that narrow under hull section effect it's performance vs. before it was added? I'm planning on designing a trimaran conversion for my Macgegor 25. Thanks!

 

Tornado plans are available.... I think.

http://www.boatdesign.net/forums/multihulls/tornado-class-plans-16156.html