Cavitation plate 2 inches below transom, worth raising?

[EddiePA]

Is it worth raising the outboard? Cavitation plate is exactly 2 inches below the transom. This is on my Sea Nymph 12K with a 15hp Johnson.

 

[onthewater102]

How hard would it be to do?

 

[SumDumGuy]

throw shims (2x2 or 1x2) under the mount and see if there is performance improvement.
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BTW and this is for everyone!!!

there is no such thing as a cavitation or anti-cavitation plate (contrary to what anyone says on this board or any other). The plate that is talked about on the lower portion of the motor leg is correctly identified as an anti-ventilation plate.
Cavitation is when you boil water on the prop and ventilation is when you suck air from the surface through the prop.
just sayin' ....

 

[EddiePA]

Because of the shape of the top of the transom and mount of the outboard, I don't think I can simply add shims. Adding a shim to the top of the transom would cause the mount to interfere with the rolled top portion of the transom and cause the mount not to sit flush against the transom. A mini jack plate would probably be the solution to raise the outboard if I decided to go that route.




Top speed of the boat with me (165lbs), associated fishing tackle, anchor, 55lb thrust Minn Kota, marine battery and 4 gallons or so of gas is 29mph, so it's not like the boat is hurting for speed. However, I wouldn't mind making it less likely of hitting bottom or other debris in some of the shallower areas I fish. Less fuel usage is also always a plus. If it picked up a MPH or two, I certainly wouldn't complain.

 

[lckstckn2smknbrls]

Yes raise the motor. I'm using a T&H Mini-Jacker.

 

[shane@]

Here is one I built for for my motor

 

[onthewater102]

performance and efficiency will be better - by how much I can't say for sure

 

[EddiePA]

Thanks, guys. I ordered a mini jack plate. I'll report back with results once installed.

 

[whitetailhntr]

29mph!!!! Nice

 

[EddiePA]

Jack plate arrived today. Should I mount it with or without plywood between the plate and the transom? The wood that I have on the transom now is too narrow for the jack plate to mount to it. Need to know if I have to replace it with a wider piece or ditch it all together.

 

[JMichael]

I would replace the wood with a piece big enough to fit the jack plate.The wood provides a big portion of the transoms strength.

 

[EddiePA]

JMichael » 24 Jul 2014, 22:12[/url]"]I would replace the wood with a piece big enough to fit the jack plate.The wood provides a big portion of the transoms strength.

My thoughts as well. Thanks.

 

[onthewater102]

depends on if there is wood on the inside of the transom too - I see in your pics there is a plank outside, but what about the opposite side?

Also - I've seen guys run two strips of 4' 1/4'' thick aluminum angle horizontally on the inside of the transom where the two bolts come through in place of the wood. Makes for a permanent transom stiffener for about $50 delivered from www.onlinemetals.com (buying 8' and cutting it yourself)

 

[EddiePA]

The inside just has a small piece of 1/2" birch at the top of the transom where the outboard clamp mounts.

I hope to stop by Lowe's today to buy more 3/4" birch to redo the transom.

 

[EddiePA]

Finished the install (for the most part). Plate is level with the bottom of the transom in this position. Got it all done in a day, including removing the transom wood and building/installing a new, larger piece. Hope to test her out this week, weather permitting.

 

[lckstckn2smknbrls]

With the 4" set back from the mini-jacker you can raise the motor 1inch to 2 inches higher.

 

[EddiePA]

I have the plate set up to raise the outboard an additional inch or so if needed.

 

[JMichael]

Lets us know what the new top speed is when you have it fully adjusted.

 

[whitetailhntr]

Thanks, guys. I ordered a mini jack plate. I'll report back with results once installed.

What was the coat of ur jack plate?

 

[whitetailhntr]

Cost