View Full Version : CMC Tilt and Trim Unit

06-16-2008, 03:09 PM
"The factory tilt and trim motor (1975, 115 Johnson) is getting weak and I am toying with idea of installing a CMC 130 unit. However, I am concerned about it moving the engine 5 or so inches aft of the transom. It seams to me this will add a bending moment to the transom and add stress to it not to mention the offset forces of thrust and turing. The transom is in good condition but it is a 33 year old boat too.
Should I be concerned about this or are the added stresses neglible?
CMC indicates that an improvment in performance can be expected because the motor can be raised higher.
Any input is appreciated? Thanks, Mike"

07-23-2008, 09:42 AM
"mike,u r correct about the added stress...the movement back 5" changes the fulcrom point,..as well as the added weight,...adding the CMC unit,is THE way to go on those older engines,but,u may very well need to beef up your transom."

07-23-2008, 11:35 AM
"JWB, Thanks for responding.
The transom is two 3/4" plywood pieces sandwiched with fiberglass between as well as fiberglass encapsulated. There is a molded in motor splash well that should add some stiffness. Presently, I have an 1/8" alum plate between the motor mounts and the transom. I can add alum plate on the inboard side of the transom.
I did buy the CMC, but haven't opened the box. I wanted to see if there is enough steering cable slack, before I get committed."