youdirtyfox

Hi guys, just looking at different mounting options for my cat build.
I came across this, but me being me I dont understand how it attaches to the hull? does it still need stringers?

Thanks
Sam.

Sean Bowf

Looks like they want you to mount it by putting screws up through the bottom of the hull...

Sean

ob nut

My Feedback: (1)

While I don't do mono's, never seen a mount like that. Believe it to be home made. DON'T put the screws thru the hull..

Most mounts have basicly what you have, but don't use the outter bracket. Instead, there should be ply wood rails to mount the engine mount to. Measure the distance from the rubber mount to rubber mount, outside that is. Then glass in two 3/8" ply that distance apart. Might be a good idea to figure out where the mount holes will need to be drilled in the wood rails before glassing in.

Certain others will join in...

youdirtyfox

Ar right cheers Sean, looks very unorthadox compared to what I have seen on here then (stringers/rails)

ob nut - I havent bought it and it is'nt a home made item, although I will probably make my own I didnt think putting screws up through the hull was a good idea really also, even on a cat ?!?!

Dan S

nothing wrong about mounting an engine mount through the hull, this is how every SSP21 and 40's from Phil are mounted, not quite that mount but similar.

Dan.

glennb2006

Hi there Dirty Fox,

What you do, is align the shaft and coupling carefully, tack the posts onto the hull with epoxy, or cyano if you prefer. Remove the motor and the rest of the mounts from the hull, and bond the posts in with glass and resin or epoxy and glass, depending what your hull is made of.

Then simply bolt the four fixings back into place to remount the motor.

No holes drilled through the hull. Check the rest of the Prestwich site and you will get full detail of how to mount a motor using this method.

This is fairly standard practice on FSRV boats. Nice mounting, light and strong. There are alternatives to heavy 5" rails in boats!!

Glenn

Ron Olson

My Feedback: (1)

For a Cat hull it should work fine but just a little unorthodox for us Americans. If it needs to be bolted through the hull you can always use button-head bolts to streamline it.
Yes, Phil Thomas' Sport 20 mounts the engine in almost an ideantical way and his setup for mounting the strut also has bolts running up through the bottom to mount the brackets on the hull floor.

Hydro Junkie

Most of the scale hydroplanes in the Northwest are mounted through the bottom as well. The only thing you need to be sure of is that the holes are sealed to prevent water intrusion through the sides of the bore. On a cat, that would be a little strange, but if it works..............

youdirtyfox

Great, brilliant, thanks for everyones help indeed

Now all I need to know is where to mount the motor?! does it have to be on/over the CoG , or have i get that wrong ?,lol
I read like 30-35% for cats, but dont really understand what this translates into.

any further help much appreciated.

Hydro Junkie

the 30-35% is the distance from the transom forward. If you have a 36" boat, the distance would be 10.8-12.6 inches from the transom's outer face to where the CG is supposed to be.

Ron Olson

My Feedback: (1)

27-30% forward from the transom may work out a little better but it depends on what the manufacturer recommends.