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External hull mounted water pickup for a triple outboard cat

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Old 12-19-2010, 02:09 PM
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Default External hull mounted water pickup for a triple outboard cat

I am rigging a 35 Motion with triple outboards. Are hull mounted external water pickups necessary, particularly for the center engine? i have one thing worrying me. the current location of the pickups on the sponsons is directly in the line of the bullet of the Sportmaster gearcases, would that be a problem? how do i go about this?
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Old 12-19-2010, 04:45 PM
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The trip o/b apps I did ran very high x's. Sense the need for the pickups . We ran 2 pickups to 2 trainers. Both outs from the strainers went to a manifold which had been plumber for triple outlets. From there each outlet was plumber to each engine below the adapterplate . We ran 6" cooke brackets and the boat had no center sponson. Typically the center engine will bang the limited about 500% more. We used 2.5 280's on this app. We did another using 300x s and shared to center cases. Ended up adding a small center sponson. Same water system. A lot, A LOT of time in these skates, but they were fast.
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Old 12-19-2010, 08:14 PM
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Chsudon, Why do you need water pickups when the Sportmasters have the water intakes on the bottom of the bullet ? Won't the l/u be lower than the hull to pick up water ? "HIGH LIFE"
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Old 12-20-2010, 01:21 AM
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On my brother in law ,s 32 Skater ,the lowers were so high that there was not enough water coming tothe low water pickups,if we took a straith edge and hold it along the bottem in front of the bullet ,the point ( shaft center) was about 2 1/2 -3inch above the bottem,external pick ups exactly like Monstaa ,s boat ,and indeed these boats run extremly fast with triple 280,s and 14 1/2 x 34 and 1,75:1 ratio installed we ran 126 mph
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Old 12-20-2010, 02:36 AM
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Default Water pickup

My system is set up the same way monstaaa described, with water from the pickups going up to a manifold which then feeds the engines directly to the block. I have no strainers. What about the pickup being in the line of the gearcase?
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Old 12-20-2010, 11:01 AM
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Quote:
Originally Posted by Chaudron View Post
I am rigging a 35 Motion with triple outboards. Are hull mounted external water pickups necessary, particularly for the center engine? i have one thing worrying me. the current location of the pickups on the sponsons is directly in the line of the bullet of the Sportmaster gearcases, would that be a problem? how do i go about this?
I would try and locate the pick-ups so they do not disturb the water flow in front of the prop. It may not be an issue, but ideally you have a smooth flow going to the prop to prevent any cavitation or efficiency loss.

I had a twin engine Talon 22 and slowly kept increasing my engine height (in 1/8" increments) until they started losing water pressure at speed. Installed hull mounted pick-ups and kept going up. The higher I went, the better the handling, acceleration, and top speed. 2" above the bottom was the sweet spot for my rig. Any higher and I started losing handling and efficiency.

I installed strainers and check valves in each line (they are mounted to the jack plate). Without the check valve, at idle when you are not moving the water being pumped by the impeller will take the path of least resistance and simply flow out the hull mounted pick-up, not the engine block.

The pick-ups were adjustable and very slight adjustments made a big difference in water pressure.
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Old 12-20-2010, 12:15 PM
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Your Talon has a center pad ,and that is a perfect place to mount those external pick ups ,so they don,t disturb the pad in front of the props .
My twin engine 26 ft cat has no center pad ,and I did also raise the engines up with the bullets (centerline propshaft ) to 2 inches above the boats bottem,so I drilled two 5/8 holes thru the bottem in a +- 30 degree angle with a stainless 5/8 tube welded to a 1/4 inch thickstainless plate that is epoxied and glassed in place from the inside .
The stainless tube sticks out 1/8 inch (outside )
I drilled them 5 inches more to the outside of the sponsons as where the center shafts are , I mounted check valves too like Formulafastech did ....still I have only 8-10 psi water pressure ,it looks like the tube doesn,t stick out enough under the bottem .
I have no idea if the pickup disturbed the prop,but have to say they are 15 inches more up front than the transom edge.
I run pretty efficient with 15x34 three blade cleavers at 7800 rpm 1,87 ratio and 112 mph
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Old 12-20-2010, 04:04 PM
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Valves as stated. Pickups we used were 18-20 inches forward of the notch close to the tunnel. Thru the bottom with a cone shape carved in the hull to make the trailing edge not disrupt prop water.
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