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Old 25 July 2008, 16:17   #11
Country: UK - Wales
Town: North Wales
Boat name: VosPower 115
Make: Pacific 22
Join Date: May 2004
Posts: 9
Hysucat Engine Mounting

Hi George

I have a 2001 6.5 Hysucat. I have rigged a Tohatsu 115 and am having the same running problems as you i.e some pitching at 25Kts and occasional dropping off the front foil and nose diving . I have also noticed excess spray at speed and wonder if the engine is mounted too low, I have it on the lowest position.

It looks like my boat was first setup with twins judging by the holes in the transom. The last owner ran it on a single engine and appears to have fashioned a fibreglass pod to reduce the drag on the leg, it looks home made.

Let me know how you get on with your setup, I am planning on going for the highest but one engine mounting and see how that goes. Should be in the water next week.

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Old 25 July 2008, 19:40   #12
Country: USA
Town: Santa Barbara, California
Make: Hysucat
Length: 6m +
Engine: Yamaha F115
Join Date: Jun 2008
Posts: 6

Replied to your PM. I will try to upload some pictures to the Gallery in a few days.

My boat is extremely stable. How much weight do you have in the aft locker?

When the boat was new I used 6 gallons of fuel and a jetski starter battery in the stern locker and a couple of life jackets. No gear at all. We played around with the engine height, getting 50kts with two adults at the helm. The stern would wobble at WOT as she floated on the back foils, pucker time, with the engine all the way up, she would also bow dive easily. Lets say with fuel, batteries, large pre-filter, in-line blower etc. The stern locker now has 246 US LBS. in the locker +-. 15 US LBS. under the helm seat in safety gear, 20 US LBS in the console interior, gauges wiring, 12volt subsystem and VHF radio and a small anchor and in the bow.

The Yamaha F115TLRY is 400 US LBS. with 25" shaft, mount all the way up.

I assume a 2001 model has sail tracks in the deck so the console can move. Measuring from the bow to the interior of the console wall, seat down, I have 11 feet 3.5 inches.

Hope this helps.

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Old 18 August 2008, 11:14   #13
Country: UK - Scotland
Town: Glasgow
Boat name: TwoGees
Make: Ribtec
Length: 6m +
Engine: Mercruiser diesel
Join Date: Sep 2003
Posts: 72

I have now had some guidance from Malan Conradie, the original designer of the Hysucat.
My hull is a 2005 and has the single engine pod incorporated in the moulding. Yours being a 2001 needs the pod attachment which you seem to have.
The engine needs to be a long shaft [not extra long shaft as mine is] and the cavitation plate should be roughly at the level of the rear hydrofoils. I have been advised to use a 22-24" cleaver prop for the 150 Yam on my rig and to add dolefins to the outboard.
Once I get this lot sorted out and sea trialed, I will post the results here.
Hopefully I will be adding one of the big smiliey faces.


Anyone got a Yam 150 long shaft gearbox?
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Old 27 August 2008, 07:48   #14
Country: France
Town: Cannes
Boat name: midkat 550
Make: apoge
Length: 5m +
Engine: 2x50 Tohatsu
Join Date: Jan 2008
Posts: 126
georgec, when I started reading your post 5 minutes ago, my first idea was "why a 27" leg (or 25", I think 27 doesn't exist) on this cat, it should be a 20" !"

Now I see that you have the right answer from MC/

I would rig the heigth by putting the anti-ventilation in line with the bottom edge of centre V of the hull, or possibly 2cm below.

I would suggest a prop like Powertech OFX3 or 4, VMS3 or VMX3 which are made to run very high
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Old 16 June 2009, 04:22   #15
Country: Other
Town: Harare
Boat name: Spirit Wind
Make: Stealth Cat
Length: 6m +
Engine: 75hp Mariner ob x 2
Join Date: Jun 2009
Posts: 2
Hysucat 6.5m over reving & Cavitating

I bought a 6.5m hysucat from South Africa (Malan Conradie) in 2003. Originally it came with 2 x 60hp Mariner big foot outboards. These worked very well but with 6 adults up, fishing tackle and dive kits it struggled a bit.
I recently upgraded the motors to 2 x 75hp mariner outboards. The new motors have 19' props and the first trip to Mozambique (sea level) had the motors over reving and cavitating at full power and also on the plane. I have ordered 21' props to see if that makes a difference. I also plan to get two manually adjustable jack plates and put these on and adjust the motors up and down to see if they make a difference. The jack plates will no doubt push the motors a bit further out at the back which will chnage the CG but I am not sure how big an effect this will have on the overall performance.
Do you think I am heading in the right direction with regards to the over reving and cavitation ?
Any help and suggestions would be greatly appreciated.

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