by Harry T. Larsen

(Last Update 1 Sep 00)



Designed and Built by...

Harry T. Larsen

7103 SE 32nd

Mercer Island, Washington 98040

206-232 9073 or 206-773 5591

email: talaria@foils.org

website: http://talaria.yolasite.com/

Yes, this boat still exists and is for sale to the right buyer!

Boat Specifications...

Hydrofoil System...


Owner's Comments...

I have found that most people who call/ Email are enthusiasts or would-be designers / builders; that is they want to build a hydrofoil, not buy one. When asked the cost, I answer that to convert a 24 foot outdrive-powered craft such as TALARIA IV would be about US$20,000. Not expensive, in boating terms, but beyond the casual hobbyist's budget. The callers are usually deterred when they find out it requires an autopilot. If so, I suggest the Hobie TRIFOILER mechanical submerged foil concept or the Russian and Florida model boat hydrofoil surface piercing design concepts as approaches to consider. The bulk of the questions I receive are about the hydrofoils, an area where I have little knowledge; my background is better in the fields of automatic control, hydraulics, analog electronics, and software. I have had a few persons in the Seattle area or visitors stop by to see the boat. If mutually convenient I can take them for a ride (it is kept on a trailer). I am pleased talk with anyone who I can be of help to. Regarding the sale of kits/conversions, the market interest has not so far been sufficient, i.e. no one has expressed an interest in buying a kit. Notably, no one has asked about buying the boat either.

[6 Mar 00] I have added more pictures of TALARIA IV to my web site. Also a parts list with approximate cost. Specifically it is a "complete" parts list with all sub assemblies The cost is the cost of the part and all its sub parts - an indentured parts list. As such, one can see the cost of any sub part, e.g electronic, hydraulics, structure, or element of that sub part. Each part's cost includes all of its sub part costs but not its assembly labor cost on the boat. The "System" cost is the sum of the cost for all hydrofoil-related parts in Talaria IV. For example, the aft foil cost is the cost to cast the foil and the labor cost to machine it. It is intended to be an estimate of what someone would pay to have that part made, ready to install on a boat. It may be useful to builders for their better understanding of the cost of the various subsystems. -- Harry Larsen (talaria@foils.org)

Independent Assessment of TALARIA IV...

[7 Jan 99] When I was last in Seattle I had the pleasure of not only meeting Harry Larsen but actually getting to ride in his hydrofoil TALARIA IV. This is the first time I have been able to ride one foilborne and I can tell you it is amazing! When she is sitting in the water it is not obvious that she is very different from any other cabin cruiser. The fully submerged foil system is controlled with a custom build analog computer using an inclinometer (pendulum type device) for roll control and a front mounted ski type of mechanical height control. Mr. Larsen tells me it was an important design criteria not to use expensive aerospace equipment like gyros. Propulsion is provided by an extended I.O. The system is fully retractable and appropriate measures have been taken to minimize damage from drift strikes. Exiting the harbor was much like any other at a slow pace to minimize wake, advancing the throttle, the small block chevy revs smoothly and then becomes slightly louder as the exhaust rises out of the water. The change from hull to foil is not felt so much as a lift sensation but more like some one let go a trailing line that was towing an anchor. The motor revs up with the reduced drag and the boat speed increases. looking aft, the wake nearly disappears. You feel a change in the ride immediately as the waves seem to vanish. there is still some feeling but it is as though you just went from riding in a buckboard wagon to a Caddy. The slamming of waves normal to crossing the wake (we went looking) was completely gone. The real difference was when he let me drive. As the craft became foilborne the response to the helm changed from the feeling of driving a boat to that of flying an aircraft. Albeit a small aircraft that had rudder input tied to the ailerons as a few do but it I found the similarities amazing. Turning the helm banked the craft and directed the boat into a turn with a minimal of lateral acceleration. A very tight turn was possible without stalling. I was most amazed at the stability and feel of control, after becoming comfortable there is no doubt that you could cruise at speed right through most traffic with confidence which Mr. Larsen demonstrated at he took her back into the harbor. He tells me that while it is safe and there is less wake than at all but idle speed hull borne the problem with such a maneuver is that it will scare the wits out of others in the harbor to see this big cabin cruiser moving at 25 knots so close. It would result in someone immediately calling the coast guard or harbor master! Fortunately for us this was a cool fall day and there was no one else around. This would be the perfect answer to big lakes like The Lake of the Ozarks that are nearly unbearable due to the rough conditions from so much traffic. I simply find it ridiculous that there are so few hydrofoils out there. This is a gold mine I swear. For no more than it would cost to have a conversion done, after riding Mr. Larsen's boat there is no way I would spend the kind of money a cruiser of that size cost without having it fit with foils! -- Elliot S. James (esjames@cvalley.net )



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International Hydrofoil Society



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