Prop Slip & Transducers

[AndrewM-Fishing]

I thought I'd share in hopes of helping anyone else chasing slip.

I've been chasing prop slip on my zx202c all year. It's powered with a 96 Johnson Venom 200 25p Tempest Plus. This should be low to mid 60's based on 12% slip. Right now I'm around 25% slip 50mph @ 5200 rpm. She runs really flat even with the tempest. Height on jack plate doesn't make a difference. Lots of $ spent so far.

So I stumbled across a post yesterday about a guy losing 10 mph after having new graphs installed. Turns out the shop installed the transducer inline with the prop's water column which in turn aerates the water causing slip. Did a little more digging online and then obviously marched outside to take a look at my setup. Palm directly to forehead. I had installed my transducer in place with the previous one (previous owner installed) which is off center but still inline with the prop.

I have not been out to run after I moved the ducer but I have a good feeling I'll get the lift needed to hit the 60mph area. Only down side is now working the jack plate again to find the actual happy spot. I'm heading out Friday and I'll post the results.

[limit5bass]

I would start out at 2.5" prop to pad height.

[Thamelau]

Keep us updated. I've wondered about this.

[AndrewM-Fishing]

I'm going out Friday and report back. I've asked around today and a friend of a friend had a 21ft Triton that lost bow lift after a transducer was installed. Seems to be a legit issue.

[Snakebit95]

Yep, I have experienced this on one of my previously owned boats. Removed the transducer to check if this was the problem, and sure enough it was. Good luck and let us know what you find.

[wmitch2]

Hmmmm !! Very interesting !!! Now I gotta check this out too !!

[AndrewM-Fishing]

Well just got back in from a quick speed run and I'm completely blown away. Hole shot was close to the same but I think I need to open one port a bit. As soon as I popped on top I could feel the difference. Went from 50mph @ 5200rpm 25% slip to 62mph @ 5800rpm 12% slip. I think based on today I'll need to drop p2p and put on a 24p. I can turn this motor to 6400 so I do have the potential to hit 70. I can't believe I've been chasing slip all year for it to come down to a transducer...

[WA-fisher]

That's good news. Do you have any pics of the previous transducer location that was causing the problem? Do you think mounting on the side of a jackplate is far enough away to not be an issue?

[castforcash]

Well just got back in from a quick speed run and I'm completely blown away. Hole shot was close to the same but I think I need to open one port a bit. As soon as I popped on top I could feel the difference. Went from 50mph @ 5200rpm 25% slip to 62mph @ 5800rpm 12% slip. I think based on today I'll need to drop p2p and put on a 24p. I can turn this motor to 6400 so I do have the potential to hit 70. I can't believe I've been chasing slip all year for it to come down to a transducer...

Good news! Yep, a lot of people just can't believe that little bit of water disturbance from a transducer will rob so much performance.

[hulapopr]

Well just got back in from a quick speed run and I'm completely blown away. Hole shot was close to the same but I think I need to open one port a bit. As soon as I popped on top I could feel the difference. Went from 50mph @ 5200rpm 25% slip to 62mph @ 5800rpm 12% slip. I think based on today I'll need to drop p2p and put on a 24p. I can turn this motor to 6400 so I do have the potential to hit 70. I can't believe I've been chasing slip all year for it to come down to a transducer...

Unless it is built to turn 6400 it will
not last long and will not be of
benefit.Dropping pitch will
Increase rpm but you aren't
gaining speed.

[MikeCSr]

That's good news. Do you have any pics of the previous transducer location that was causing the problem? Do you think mounting on the side of a jackplate is far enough away to not be an issue?

Yes please post pics of before and after as my transducer is pretty close to center which is mainly due to more room there.. I have been planning on moving it as I have had some prop slip issues too but just contributed it to the warm summer water.

[Paintworx]

My sidescan transducer is mounted to the bottom of my hole shot plate on the bottom of my 10” Bobs jackplate. It hangs down about 3” below the bottom of the plate. Boat is a 521VX Ranger. The stepped pad hangs down 12” below the transom/jack plate. This seems like a solid way to mount the transducer without effecting the performance since that part of the boat/jackplate is out of the water at speed.

[JR19]

Good news! Yep, a lot of people just can't believe that little bit of water disturbance from a transducer will rob so much performance.

My side scan transducer mounted to my jackplate robbed my motor of water pressure. It had no effect on speed but in long sweeping turns my water pressure was weak enough I would get an occasional over temp alarm. In a straight line I notice a small drop in pressure but never got an over temp alarm. I change my water pump thinking it may be weak and the problem was the same. Then one day I got to thinking what has changed...ding I installed side scan on my jackplate. I removed the transducer and went for a test run and gained water pressure and never had an alarm in a long sweeping turn. On my particular motor I can increase my inlet screen size to gain water pressure. Doing this fixed my issue and let me keep my transducer in place.

[AndrewM-Fishing]

Unless it is built to turn 6400 it will
not last long and will not be of
benefit.Dropping pitch will
Increase rpm but you aren't
gaining speed.

I have to lower the jb because at just about 1/2 trim my water pressure starts to drop out and rooster tail starts getting a little high. The bow has lift now that the prop is biting but from the way she's riding she needs a bit more to really let lose and scream. Lowering the JP is going to lower my rpm but getting the extra lift / more hull out of the water might help increase rpm at the same time. Dropping a pitch or two might be necessary to achieve optimal wot rpm range but it's going to be trial and error. The motor is not stock. I've done reeds, cooling mod, and fine tuned the jetting. Reeds are good up to 6500.