Thrust to Hull

[Two Duffs Daisy]

I am in the process of converting an inboard Four Winns Freedom 195 vessel to outboard. I would like to know how the thrust of the inboard engine was transferred to the hull. Is it through the transom or is it through the engine mounts, or both?

 

[jimmbo]

Welcome to iboats

Well, it depends on what kind of an Inboard it was. An old style Inboard, where the Prop Shaft runs through the Keel of the Boat, the Thrust would be transferred through to the Engine Mounts. An I/O, that would depend on the Brand, and the Year of the Engine. Some like the pre-Cobra OMC used the Motor Mounts, bolted to the Stringers. Post Stringer OMCs, Mercruiser, and VP, models, all used the Transom.

 

[Two Duffs Daisy]

Thanks Jimmbo, prompt reply appreciated!
I’ll do further research!

 

[Two Duffs Daisy]

Thanks Jimmbo, prompt reply appreciated!
I’ll do further research!

Thanks for the kind “welcome”

 

[tpenfield]

I'm going to go with 'transom' since the drive shaft is not fastened to the engine coupler (merely a spline coupling). So, the outdrive has no way to apply forward pressure on the engine. The force of the outdrive is transferred to the gimbal ring and to the transom assembly of the outdrive.

For an I/O to OB conversion, you will need to consider the torque that an OB places on the transom, which would be greater than an I/O setup. If you look at some engine bay pictures (online ?) of traditional I/O boats that are offered as OB, you will get an idea of how the boat manufacturers deal with this.

 

[Two Duffs Daisy]

I'm going to go with 'transom' since the drive shaft is not fastened to the engine coupler (merely a spline coupling). So, the outdrive has no way to apply forward pressure on the engine. The force of the outdrive is transferred to the gimbal ring and to the transom assembly of the outdrive.

For an I/O to OB conversion, you will need to consider the torque that an OB places on the transom, which would be greater than an I/O setup. If you look at some engine bay pictures (online ?) of traditional I/O boats that are offered as OB, you will get an idea of how the boat manufacturers deal with this.

Really Great info thanks guys!
Just looked at the transom thickness, it’s substantial, well over 3 ins, the existing engine mounts would never support fore and aft thrust, so my question has been answered, many thanks Guys!
Great Forum!!