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Old 25 June 2008, 08:45   #1
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Hysucat 6.5 engine mounting

Anyone had experience of fitting a single outboard to one of these South African catamaran ribs?
I have fitted a 150 Yamaha four stroke long shaft [27"] and am having problems with excessive spray at the rear being forced past the engine and over the rear transome. The boat also tends to dive occasionaly as if coming off the plane on the central Hydrofoil.
I have tried trimming in and out and have also adjusted engine height by one hole to no availe, although by getting a couple of chums to act as moveable ballast we did get a taste of what this baby can do by moving their weight forward.
Thanks
George
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Old 25 June 2008, 08:49   #2
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Quote:
Originally Posted by georgec View Post
Anyone had experience of fitting a single outboard to one of these South African catamaran ribs?
Try getting in touch with TIM, gavin or Charles (all from RIBnet): all have had the Hysucat, although I'm not sure what engines they had. It might be worth PMing them as they haven't posted here for a while.

HTH
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Old 25 June 2008, 09:04   #3
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Thanks Louise
I'll give that a try
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Old 25 June 2008, 16:26   #4
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Hysucat

Hello George
I don't frequent these parts much anymore; well done on acquiring a very tough, seaworthy craft. Although I owned a twin set-up I helmed many single installations in SA. The builder, Malan Conradie is a personal school and army friend of mine. I am sure he would give you all the advice you need.
First off, no-one would believe this story; we found anyone sitting on the aft bench seat always ended up with an unexplained wet back. It was becoming so ridiculous that I had my wife helm the boat whilst I hung over the transom to see how it was possible for water to effectively squirt backwards against the flow of everything. When the boat hit roughly 24 knots it all became apparent. The position of the central bung was the cause of the problem. By simply rotating it so that the ‘butterfly’ end is vertical you will have solved the problem. What happens is when going along the force of the water is so great on the edge of the bung fastener the water is propelled over the transom back into the boat – weird huh?
Your next problem is the way the engine is mounted as well as the positioning of ballast with a single engine installation. If you could draw an imaginary line between the bottom inside corners of the hulls, the cavitation plate of the engine must be in line with this. We found by placing a bag or two of sand in the forward anchor locker places the boat more squarely in the water when landing. The boat is more stable and you will find driving her faster than you ordinarily would over choppy water affords a much more comfortable ride as she gets up higher on the foil.
Good luck; let me know how you get on.
Charles
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Old 26 June 2008, 11:35   #5
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Thanks Charles That is really helpful. I will give it a try and let you know how I get on.
Did you notice if this was more pronounced on the single engined rigs you have been on? Just thinking if a bung can cause such an effect what about a muckle great outboard leg.
Could you let me have a contact for Malan.

Many thanks

George
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Old 26 June 2008, 17:02   #6
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George, in reply to your question, the propulsion is irrelevant, it is the speed which is just about right to force the water in the other direction.
You can email Malan at malanconradi@mweb.co.za, although I cannot guarantee how long it would take him to reply as he runs a whale watching outfit near Agulhas now.
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Old 28 June 2008, 19:24   #7
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I have a 2000 Model of the Hysucat 6.5M built by Magson Marine. Running a Yamaha F115. I custom rigged the boat with two aluminum 10 gal. tanks (outboard) and two grp 24 batteries center, in the stern lazerette with blower and fuel filter. The engine is mounted high on the transom (fourth hole) so that the engine mounting bracket sits 2.5 inches higher than the transom lip. With two people and no gear she gives 43.5kts on the top end.
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Old 30 June 2008, 23:58   #8
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Quote:
Originally Posted by georgec View Post
Anyone had experience of fitting a single outboard to one of these South African catamaran ribs?
I have fitted a 150 Yamaha four stroke long shaft [27"] and am having problems with excessive spray at the rear being forced past the engine and over the rear transome. The boat also tends to dive occasionaly as if coming off the plane on the central Hydrofoil.
I have tried trimming in and out and have also adjusted engine height by one hole to no availe, although by getting a couple of chums to act as moveable ballast we did get a taste of what this baby can do by moving their weight forward.
Thanks
George
I had another thought on your problem. If your boat was originally setup with two motors, you do not have the single engine "Pod" mounted center stern. The "Pod" is a fiberglass fitment that makes the stern center deeper in the water. Also I know several versions and builders made these boats. Is your center console on tracks, so you can trim the CG to match your weigh distribution?
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Old 10 July 2008, 11:58   #9
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Hi

My boat was a new bare hull with a fixed consel which I think supeceeds the models with the consel on tracks.
An extension to the hull at the point of mounting the single engine would make sense as this would deflect water away from the engine leg.
You don't have any photographs of yours by any chance

Cheers

George
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Old 19 July 2008, 23:23   #10
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Quote:
Originally Posted by georgec View Post
Hi

My boat was a new bare hull with a fixed consel which I think supeceeds the models with the consel on tracks.
An extension to the hull at the point of mounting the single engine would make sense as this would deflect water away from the engine leg.
You don't have any photographs of yours by any chance

Cheers

George
Sent an email from this site, be glad to send pictures etc.
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Old 25 July 2008, 16:17   #11
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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
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Pacman,

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
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Pacman

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.

Cheers
George

Anyone got a Yam 150 long shaft gearbox?
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Old 27 August 2008, 07:48   #14
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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
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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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