Jump to content
RPM Racing

transom angle on a DR20 and a Rocket?

Recommended Posts

Does anyone know what the transom angle is on a DR20 and a River Rocket?

I am trying to figure out if I need to run a positve 5 degree wedge or jackplate to use a new style 12" mid on my river rocket. Most of the setups I have seen have been on a Dr20 and there is no angle added in. I know if you run the short trim ram in the 15" mid on a rocket you need to add 5 degrees so that you can trim out enough.



Share this post

Link to post
Share on other sites


Depending on the bow weight of your STV, you will need between 2 and 5 degrees added wedge to the transom for your 12 inch. a lighter bow will require less trim angle for best performance.

The 12 inch uses the same length ram as the OS 15 inch (the short ram). This limits the max trim angle for the engine. For many uses, this is not enough angle.

On the DR-20, many of the quicker boats either use wedge plates, or build it into the jack plate.

I am assuming you ARE going to use a jack plate. If this is so, you only need to remove the back half of the plate you have, and build new parts for the setback and transom angle you desire. Any decent machinist can do this for you out of a small length of angle aluminum. MAKE SURE the bottom of the plate does not catch water at planing speeds. A cardboard or poster board mock-up helps design what you want.

Have him build you a locking collar for the hydraulic up/down ram at the same time.

I hope this helps,


p.s. - I am having a change made to the ECU, it will be sent soon.

Share this post

Link to post
Share on other sites

Thanks Wayne, After doing some research, I was thinking of going with +5 degrees for my boat. I was planning on doing what you said with the jack plate and just get a new back half. Are your back plates solid all the way across where it bolts up to the 12: mid?? I heard that there is not very much strength in the 12" clamp bracket in this area and it needs to be solid across the back?

I will call you later this week about the ecu and the other parts.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now