Offshoreonly.com

Offshoreonly.com (https://www.offshoreonly.com/forums/)
-   Drives and Lower Units (https://www.offshoreonly.com/forums/drives-lower-units-217/)
-   -   Dual down shafts performance (https://www.offshoreonly.com/forums/drives-lower-units/372581-dual-down-shafts-performance.html)

IGetWet 07-22-2021 06:28 AM

For comparison sake, my 06 38ZR imco SCX-4s are about 2” above hull bottom. Haven’t gotten a precise measurement on height or how far back they are. They are on ITS boxes. 17.25” 5 blades 18 degree rake. Planes out good with help of 280 k planes but isn’t challenging by any means. In a video that was taken with a go pro mounted in the notch you can clearly see the tip of the lower above the water. My slip isn’t the greatest however, 15-18 percent at cruise. From my experience and shops I’ve talked to the big imcos run the beat when up high out of the water and have a 16”+ cleaver to get around the big bullet and reach the water. There’s also the handling advantage with the cleavers. My boat was set up high to begin with with long sportmasters. 100+ 4 people coolers, full of fuel. 105 light, best so far of 108


https://cimg7.ibsrv.net/gimg/www.off...fef753e0f8.png


https://cimg1.ibsrv.net/gimg/www.off...c110481d8.jpeg

b18cls1 07-22-2021 08:37 AM

i lost about 7mph but may need prop adjustments, but i have a low water pressure issue with mine, igetwet i see you have transom pickups, do you still send water through the drive to cool it?

IGetWet 07-22-2021 08:53 AM


Originally Posted by b18cls1 (Post 4798571)
i lost about 7mph but may need prop adjustments, but i have a low water pressure issue with mine, igetwet i see you have transom pickups, do you still send water through the drive to cool it?

Yes water goes through the drive only from the lower pickup. The water exits out the two holes in the front of the drive top cap.

b18cls1 07-22-2021 09:10 AM


Originally Posted by IGetWet (Post 4798573)
Yes water goes through the drive only from the lower pickup. The water exits out the two holes in the front of the drive top cap.

so the 1 1/4 hose inside is capped off?

IGetWet 07-22-2021 09:18 AM


Originally Posted by b18cls1 (Post 4798576)
so the 1 1/4 hose inside is capped off?

Correct.

b18cls1 07-22-2021 09:32 AM


Originally Posted by IGetWet (Post 4798577)
Correct.

I’ve been trying to get an answer out of Imco about this and haven’t been able to. I figured it would be ok but just trying to make sure

rvtransport 07-22-2021 09:47 AM


Originally Posted by IGetWet (Post 4798550)
For comparison sake, my 06 38ZR imco SCX-4s are about 2” above hull bottom. Haven’t gotten a precise measurement on height or how far back they are. They are on ITS boxes. 17.25” 5 blades 18 degree rake. Planes out good with help of 280 k planes but isn’t challenging by any means. In a video that was taken with a go pro mounted in the notch you can clearly see the tip of the lower above the water. My slip isn’t the greatest however, 15-18 percent at cruise. From my experience and shops I’ve talked to the big imcos run the beat when up high out of the water and have a 16”+ cleaver to get around the big bullet and reach the water. There’s also the handling advantage with the cleavers. My boat was set up high to begin with with long sportmasters. 100+ 4 people coolers, full of fuel. 105 light, best so far of 108


https://cimg7.ibsrv.net/gimg/www.off...fef753e0f8.png


https://cimg1.ibsrv.net/gimg/www.off...c110481d8.jpeg

Tori, I think you are spot on with your set up and bullets just surfacing. Most guys I know are running 15 percent slip when surfacing the propeller's. I will bet your water pickup location is causing you a little more slip also. Not sure on Donzi hull but on Fountains if you move water pickup to outside hull you will help with slip because props are getting cleaner water. Hope to see ya soon. Are running Top Gun poker run this year?

IGetWet 07-22-2021 10:49 AM

Yes we are looking forward to top gun! You probably right about the pickups down in the V, but they do scoop up enough water for the two stage pumps so I’m happy with that! I’ve asked a couple guys with NXT’s what their slip is but no one seems to know that or how high their drives are. From what they’ve told me about planing I’m betting they’re way up there though.


https://cimg8.ibsrv.net/gimg/www.off...cbe2cc3ef.jpeg

b18cls1 07-22-2021 10:57 AM


Originally Posted by IGetWet (Post 4798599)
Yes we are looking forward to top gun! You probably right about the pickups down in the V, but they do scoop up enough water for the two stage pumps so I’m happy with that! I’ve asked a couple guys with NXT’s what their slip is but no one seems to know that or how high their drives are. From what they’ve told me about planing I’m betting they’re way up there though.


https://cimg8.ibsrv.net/gimg/www.off...cbe2cc3ef.jpeg

thats where im putting my pickups at id rather get good clean water all the time deep in the v to feed my twin stage pumps

Quinlan 07-23-2021 05:46 AM


Originally Posted by b18cls1 (Post 4798579)
I’ve been trying to get an answer out of Imco about this and haven’t been able to. I figured it would be ok but just trying to make sure

Carter plumbed my drive intake water to exit out the transom. We were going to do like a drive shower placement to spray on top of drives but swim platform brackets were in the way so it comes out the center more.


All times are GMT -5. The time now is 12:04 PM.


Copyright © 2026 MH Sub I, LLC dba Internet Brands. All rights reserved. Use of this site indicates your consent to the Terms of Use.