Hobbie 18

[sysfx]

Originally Posted by aussiebushman

I'm attaching some pictures of the scale model... Comments from all welcome

What will be the boat size? And the building system/materials?
Why have foils both in the mainhull stem and the rudder? just choose one and, if not the rudder one, you might go for a pivoting dagger rudder.
If you want more comments or to exchange information, please reply directly to sysfx {at} yahoo [dot] com

Luiz

[aussiebushman]

Hi Luiz

There is a problem with this software causing the application to crash when the "manage attachments" box is opened so this message might be duplicated.

Overall boat length is 24' and the amas would be 18 so I wish to know what the alignment should be - relative to the point of lateral resistance of each hull probably, but possibly just centred fore and aft.

The foil at the aft end on the model was my afterthought - the Catri has one on the rudder. The model does not have the foils/angled blades in the amas but these would be added to the Hobie hulls in the real thing.

Regards

Alan

[aussiebushman]

Forgot to mention that the proposed build will be 9mm strip cedar or maybe Kiri. This will make the boat heavier than the real catri, but speed is not an issue for me.

[bill broome]

the woods 'strike' folds the amas up and over. horrified me. weight and windage where you don't want it, and it won't float upright with the amas in the air. now another madman. are there patent problems here, or is there some advantage i don't see?

[aussiebushman]

Bill

Re the tone of your comments, it would be appreciated if you you might adopt a less insulting and objectionable approach. The catri people have been notified of my intention to use the general concept, albeit with totally different construction methods. I accept your point about the inherent problems of "fold-up" systems and will reconsider. However, the overall trailerable width is the restraining dimension and may mean the hull beam must be reduced to accommodate the folded amas - hence the positive aspect of the foldup system.

[sysfx]

Originally Posted by aussiebushman

Forgot to mention that the proposed build will be 9mm strip cedar or maybe Kiri. This will make the boat heavier than the real catri, but speed is not an issue for me.

If speed is not an issue, why use lifting foils?

Only a naval architect can help you with design issues such as proper ama placement. My boat's amas and mainhull are the same length and perfectly aligned. F-boats, that use shorter amas like you are planning, have the three bows aligned.

As far as I know, none of my boat's features is protected by a patent nowadays.

Luiz

[aussiebushman]

Good points Luiz, thank you and you are of course absolutely right about the foils relative to my needs.

Actually, I have done more thinking about the concept and have concluded that the Catri design would end up being more costly to build than my budget allows and probably not really suited for single handed trailering and rigging. This conclusion was reached after I had the opportunity to examine a Farrier F24 on a trailer - sure as hell would not want to try to raise that mast on my own.

Looking at alternatives, the Scarab 670 might be another contender, but I suspect the build cost would be quite high and the designer does not favour donor hulls or rig.

As suggested by someone earlier in this thread, I revisited the Trinardo information. This boat has much less volume than the Catri, but it is obviously a proven design that works well with donor hulls. There will be much less interior space but the building, launching and sailing will be much simpler. Pretty sure this will be my selection and I have already started acquiring materials.

Amazing what some people throw out. We spent a couple of days on a rural property last week where the farmer was about to burn several 6m lenghts of 250 X 75 Oregon because the ends were rotten. My 4WD is set up to carry such items, so this provides everything needed for the strongback (and to finish off the building shed). I have also acquired some 12mm Brazilian structural ply at only $20 a sheet for the transom, stem and two main structural frames.

Incidentally, I did send you a private message in response to your suggestion for direct communication - did you receive it?

Cheers

Alan

[sysfx]

Originally Posted by aussiebushman

Incidentally, I did send you a private message in response to your suggestion for direct communication - did you receive it?

Cheers

Alan

Yes, and I replied. Will send it again, in case you didn't receive it.

Luiz