to deep?

[andy 1]

I am wondering if I should add a riser to the transom of my Lund boat, I am using a short shaft merc. I noticed that the motor sits very low in the. The water almost comes just over half way up the motor mounting clamp. There is an exhaust port that is submerged when the motor is lowered. As a newbie to boating I am wondering is that normal.

thanks

andy

 

[sparkbr]

Andy,

Normally you want your cavitation plate somewhere between dead even with the bottom of your boat and about 3/4" below. This is one of those things you just have to play with though, every hull is a little different and performs differently. The higher you can get your motor, the less drag your boat will have. But be carefull, once you start getting that cav. plate above the bottom of the transom, you can get into issues with both cooling of the engine, prop cavitation, and steering, as well the prop breaking out in turns... As long as you don't get the cav plate above the transom though, you'll never have to worry about any of these issues.

An easy way to play with height changes is to use plywood as a shim between the motor and the transom.


Keep us posted on your progress.

 

[Rat]

All you ever wanted to know about mounting a boat motor

Check out the guide in the link above. Sounds like you may have a 20" shaft on a 15" transom. If that is the case then you will need to:
1) Build/buy a transom adapter
B) Build/buy a jack plate
There are other things as well, like changing the lower unit, but...

I have never seen a motot that would go 5" in height adjustment, you will proly get a few inches by shimming, and every little bit will help, but you proly aren't going to get it perfect without some additional help.

Read the guide, then make a decision.

 

[Rat]

Here is the Image.

 

[Rat]

Here's a better image of it with corrected notes: