Pontoon Boat & Deck Boat Forum

I just added a 25 inch centertoon on my 22ft tahoe. Can anyone tell me the distance from the bottom of the toon to the centerline of the propshaft? Thanks

First Welcome to the Forum

I'm not sure what you are asking but... no matter what dimension your center log is, you really need a 20 inch transom on it, if you have a 20 inch lower unit. Its no different than any outboard hull. You might get away with a 21 inch transom but not much over that.

Your cavitation plate will then be at or just below the water level coming out from under your motor mount on the center log!

If you can see the transom on my re build center log (its a 24 inch depth). You can see how the transom was cut down to 21 inches.

Hope this is of some help.

I made everything but it a 20" transom and a 20" 200xs merc. Im in the second motor mount hole but the engine is low. Before I move it up I was looking for a reference measurement as it is quite common in setting up a boat to measure from the bottom to the center of prop shaft.

pic of boat

Man I would have liked to see what is to the lower right in that picture. about a foot to the right and a foot lower.

I think the measurement from the prop shaft to the bottom would depend on your prop diameter.

i'd say try it and if it is splashing a bunch raise it a notch. keep raising it until it cavitates then drop it down one.

procomp wrote:I made everything but it a 20" transom and a 20" 200xs merc. Im in the second motor mount hole but the engine is low. Before I move it up I was looking for a reference measurement as it is quite common in setting up a boat to measure from the bottom to the center of prop shaft.

The "common" starting point is usually to set the cavitation plate even with or slightly above the bottom of the transom, or in this case the bottom of the center tube. It looks like that's about where you are. If it's not blowing out yet do like R-T suggests and move it all the way up and see what happens. The last one I set up I had to re-drill the transom to get the motor as high as we wanted it.

That is the wrong motor for your boat. Please advise me on when i can pick it up for disposal.

(I wish I had a 200 on mine!)

And Bob, when you switch out your Merc 115 4 stroke for the 200, let me know when I can pick it up for disposal...

(I wish I had a 115 on my boat...)

it is quite common in setting up a boat to measure from the bottom to the center of prop shaft.

OK it just dawned on me where you were coming from.

Maybe on a high performance boat but on a pontoon that would be way to high. What toonguy said is the way to go. As high as you can get away with without cavitation!

Guys y'all let me know when you wanna get rid of those two 115's I would love to have one on each outside log!