Hydrofoil Supported Catamaran designs

[malan conradie]

I am the designer and manufacturer of a range of Hydrofoil Supported Catamaran (HYSUCAT) boats in colaboration with Professor Gunter Hoppe and the University of Stellenbosch, South Africa. We have been developing and producing these boats since 1997 with unbelievable results. Most models are capable of 50+ knots with small engins and up to 40% more efficient than conventional craft. The models consist of the following.

1. Hysucat 42' flybridge and sport cruiser (twin 420hp - 11.5ton -50 knots)
2. Hysucat 36' sport cruiser,Fishing,fast patrole(option inboard / outboard)
3. Hysucat 25' centre console, sport cruiser.(twin 90-140hp - 52 knots)
4. Hysucat 24' centre console, sport fisher.( twin 70 - 115hp - 48 knots)
5. Hysucat 26' Rib leisure/racing. (twin 70-150hp single 115-250hp -72 knots)
6. Hysucat 21' Rib standard/leisure.(twin 50-70hp single 90-140 -55knots
7 Trident 17' Rib standard/leisure (twin 30-50hp single 70-115hp-45k

I would like to sell the designs and high quality molds for someone to take these developments to the next level. Exporting power boats from South Africa is expensive and often not viable. See some of the products on www.stealth-design.com

[Kay9]

Nice boats.

K9

[royalray]

interested (right timing) asap reply to rgj@ukcompanies.org

[malan conradie]

Thank you for the reply - contact me if you need more detailed information!

[rwatson]

Puzzled - I didnt see much sign of "Hydrofoil support" at that web site.
Can you elucidate on the term a bit please?

[malan conradie]

please click design on the web site www.stealth-design.com for more design detail. You could also visit www.hydrofoildesign.com from Professor Hoppe

[SamM1234]

I see that a couple of sites talk about increased efficiency at speeds of over 30 knots. But, are these vessels less efficient at slow speeds, because of the foil drag? Or, are there any other known drawbacks of this technology, which could have made other manufacturers/designers not adopt this technology so far?

[malan conradie]

There is very little foil drag and the foil will rather assist to get the vessel on the Plane(foil) without lifting the bow. These vessels will get up on the foil between 12 to 17 knots pending on the weight. Once the vessel is on the foil you could reduce the power as the vessel will now fly on the foils with less drag and more efficient. If the vessel runs with surface props it will be more efficient above 30 knots. There is no drawbacks with the HYSUCAT system except that the smaller craft (17'-21') is more sencitive to trim in flat water. I believe that the reson for resistance is that there are bad copy products around as well as some retrofit foils on cat hulls that are not suitable. The best performance is alway the hull and hydrofoil combination design. See the picture of a 11.5 ton 13 meter vessel running at 50 knots. Note how high the craft lift out the water.

[SamM1234]

Sure looks impressive. What range of sea conditions is it possible to fly on the foil? In other words, does it have to slow down to displacement speed above a certain wave hegiht, or is this limitation the same as for a non foil assisted cat?

[malan conradie]

The smaller light models ( 17' to 26') models do not have a limit as these models go airborn and when they re entre the water the foil will create lift forces acting like a shock absorber. It is best to run a slight angle into big sea conditions to prevent foil slapping when the craft hit the crest of the next wave directly on the foil. The faster the craft run in chop conditions up to 9-11' the softer the ride providing the engin trim is correct. As for the heavy models with inboard motors it is best to cruise at 22 to 25 knots running directly into a big sea condition with strong wind to prevent going airborn. Running with a big following sea it is easy to run at the wave speed of 30+ knots. It is always best to maintain on the hydrofoil even in the biggest sea condition to use the advantages that the foil system provide.
See the pictures of some boats at high speed.

[Gannet]

Very interesting thread and I agree nice boats. I was wondering if there was any effect to maneuverability. Also, I was envisioning these hydrofoils between the floats on a floatplane. What are your thoughts on this type of application?

[malan conradie]

The foils will improve maneuverability on catamarans and also allow the craft to bank into corners unlike most catamarans. There is no negative behavior with foils except that the craft is more sencitive to trim in flat water conditions. The foils will work verywell between the floats of a seaplane providing that the ratio is correct. If the foils are to long it might create some initial drag at the low speed range. Once seaplane gets up on the foils around 15 - 18 knots pending on the weight, the resistance is very small and it should improve take of distance and possibly less power to break the water friction. No expert on seaplanes, just an observation nowing the foil behavior.

[sail4evr]

I would be very interested in a sport 210 design on a 12.5 - 13ft LOA. Do you have aything like that or is there a trim issue in such a small boat?

[malan conradie]

Unfortunately the smallest model in the range is a 17' model. Small catamarans of 12.5 to 13' is not a good idea as there is normaly a boyancy problem and they tend to suck to the water. We are making use of a unique tri-hull design to compensate for the boyancy problem as well as the turning capabilities. The tri hull models could also be fitted with the foil system to improve performance. It would be possible to develop a small tender type boat for yachts that could be driven with a single outboard or jet type drive.
Please contact me for more information as i believe that there is a big market for a this type of craft.

[sail4evr]

I agree, I think there is a market if the price is right. Well I am very interested, but this site will not let me email you directly. You can contact me at joe@sv-seaoflove.com