Catamaran RC65 Adrenaline - 65M class - build log - RC Groups
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Aug 15, 2009, 10:09 PM
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Siri's Avatar
Build Log

Catamaran RC65 Adrenaline - 65M class - build log

Inspired by cat pictures from fellow sailors and the success of my 65cm tris I have started a 65cm catamaran build and will share the building progress here.
I'm laminating the hulls now, first pictures will be here soon.

Last edited by Siri; Aug 15, 2009 at 11:31 PM.
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Aug 16, 2009, 10:34 AM
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Dick L.'s Avatar
Hi Siri -

Well - I was back to working on my cat last night, and my initial feeling is the 65cm size might be a bit too small for a cat. Whereas your trimarans housed your gear in the center (wide) hull, the long, narrow beam-to-length ratios of a cat are presenting some interesting challenges.

I finished up the GWS drum winch, and my modified drum at just over 1 inch will fit the hull, but is a bit heavy - I probably have room for rudder servo and may have to put batteries and receiver in other hull in order to maintain balance. It looks to be a very tight fit.

I don't want to go too much smaller for sail winch, as I'm running in the 250 sq, in, hi-aspect ratio sail, so it is possible I may have to trash my ideas for hull mounted radio gear and resort to some sort of (ugly) central pod.

I really think that a 1 Meter size would provide the extra room and buoyancy without a doubt, but then I am moving back to my original 1 Meter and that is a pretty big boat!

As you start to bring a hull design together, let me know your thoughts - and what radio gear you think will fit. I know I can downsize, just not sure by how much. Heck - I just may decide to go with an extended arm on a small servo and live with it. Actually, do not need a full-out winch, as most downwind work is similar to beating - sails close hauled and seldom at 90 degrees to centerline of boat.

Aug 16, 2009, 08:52 PM
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Siri's Avatar
Hi Dick,
I got my inspiration from this Mini40 CAT - I plan to build mine with the same concept - two hulls with a center daggerboard and rudder.

65cm is very small for a CAT especially if you're trying to downscale a full size design like A-class CAT.

I'm going another way and use the hulls from my Tris instead. May look less sleek but my intention is not building a scale model but a well sailing CAT.

I will use a standard arm servo for the sheets as I do with my Tris, it has proven to be sufficient, easy and fast too.

I will setup the servos and receiver in one hull and the batteries in the other hull to balance the CAT - there is no other way without adding lead.

I expect the CAT to be much more difficult to sail as it will capsize easy unless you make it 1m wide what will look very ugly then.

Anyway build your Flyer and do the sailing tests - we cannot make much progress if we do not have anything to compare.

Aug 16, 2009, 09:20 PM
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Siri's Avatar
I have laminated the two hulls for 'Adrenaline' using the moulds from my 'Armageddon' .
I laminated the hulls plain without gelcoat to save weight.
The beams are test fit already.

Next step will be radio installation and building the rig.

Aug 22, 2009, 11:53 PM
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Siri's Avatar
Hi folks,
I made some progress on my 'RC65 Adrenaline' project. I have created the center platform to attach mast, daggerboard and rudder from 6mm carbon fiber tubes secured to the beams with carbon tows and a little epoxy, have installed the mast & keel boxes and rudder tube and fit the fin and rudder.
I also build a new rig from 6mm carbon tubes.

Here are the pictures:

Center platform with mast box, keel box & rudder tube installed

Keel and rudder assembled

Mast attached - total weight now 375g

Next to do:
  • R/C installation
  • Sails

Have a nice day
Aug 23, 2009, 11:57 AM
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nigelpheron's Avatar
That looks absolutly awesome. Very detailed building and high-tech ideas.

I'm currently working on a small cat as well, and your posts are very inspirational. They make me want to build, and experiment even more.

Good work.
Aug 24, 2009, 05:48 AM
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Siri's Avatar
Thanks for the praise, Nigel.
I will keep you all up to date about my progress here.
Would be a perfect idea if all who are working on a small multihull would post some pics and the concepts of their designs here, this way we could learn from each other and can improve our designs faster .

Aug 24, 2009, 07:47 AM
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nigelpheron's Avatar
Yes photos.

I'm still in testing ideas stages; but when things are ready, pics will follow in their own thread.

Aug 24, 2009, 01:00 PM
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Dick L.'s Avatar
Please note: This is the catamaran design I am following. Original intent was to "bury" radio gear in the hulls (2" wide") but size of some items a bit too large and will create an imbalance is floating attitude. I have decided to move to a "central pod" - looks like crap, but at this size there aren't many options.

Siri and I have had discussion/correspondence. Have started working on the pod - but family crisis this weekend - our little Sheltie (dog) passed away very suddenly, and family is in a real "down" mood - so will be detained for a while until we can get over this loss.

In the meantime, here is my hull design - based very loosely on the "A" Class current design thinking. At first, I believe I will give up some extra sail area for "safer" sailing. Can always change rig or add jib. Haven't looked at proposed 65M rules lately to see what the sail area maximum is (if any) or if they are following the monohull (RG-65) rule. Probably will use a duble-luff mainsail and not worry about rotating anything. Also first boat will probably retain wood dowels for cross-beams.
Aug 24, 2009, 01:05 PM
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Dick L.'s Avatar
A response to Siri & centerboard.

Since we all know a single hulled catamaran (windward out of water) is much faster than both hulls in, I have dcome up with the thought of allowing the centerboard to let the hull tilt "slightly" - and only enough to allow windward hull to rise from water. Have come up with a way to restrick degree of sideways centerboard movement to (roughly) 10 degrees which should allow windward hull to rise free of water, but not far enought to provided added momentum to capsize to the side.

Again - kind of busy and refocused at the moment - but when time permits I will try to mock-up my idea.
Aug 27, 2009, 01:04 AM
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Siri's Avatar
I found some time to place radio equipment. The rudder is moved with a carbon push rod, all the R/C equipment except batteries sits in one float, the battery is in the other float to keep weights balanced.
I will go for a set of easy sails and hope to launch at the weekend.

Here are some pics from my last progress.

radio tray

some views of R/C installation

rudder with pushrod attached

top view with all rc installed - you can see batteries are in the right float, while servos and receiver are in the left float

Have a nice day
Aug 29, 2009, 08:47 PM
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Siri's Avatar
Yesterday I maidened the RC65 'Adrenaline' Catamaran.
I'm happy with this boat.

video clips from the launch are on my web now:

Adrenaline First Launch

Have a nice day[]
Aug 29, 2009, 08:57 PM
Taking care of the pond.
Great video, looks good on the water.
Sep 08, 2009, 07:15 PM
Registered User
Siri's Avatar
sails cool too

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