So we decided to install a rail kit in Bebo's Hondo. My question is how do I find the elevation that the horizontal part of the rail gets installed at? I assume that some vertical distance can be made up in the mounting plates, so a little too low is better than a little too high.
Second question, the angle for the mount is aluminum, but the flat bar bracing on the outside of the stringer is steel (less cash), will this cause a problem due to disimilar metals? We will be using SS bolts.

Thanks

Frank

I am not sure what you mean by "zero out the boat at the stringers". Do you mean making the stringers level fore and aft and using that as the starting point? Thanks for the info BTW.

Frank

pics Frank pics

Hey Tio..are we working on a jet   Fwiw I wouldn't drill all the holes until you know you have it sitting right.

My rails are as low on the stringers as they can get... IMO there is no way to know where until you mock it up..

if i remember correctly, if you zero out the boat at the stringers, your pump sits at 4 degrees....so put your motor in at 3 or 5 degrees.

When I was dorking with my driveline and motor mounts, I got paranoid about just taking for granted what the factory castings were supposed to be, so I eventually came up with a fairly EZ way to measure what angle the pump was set at relative to the stringers.

I don't like the REAL EZ way which is to use a protractor/level - FWIW there's only 6 inches worth of contact to try to get an accurate reading on a very shallow angle. Not a good situation in my opinion.

Like Brad sez, zero out your hull so the top of stringers are level. Then, clamp some kind of straight edge vertical onto the face of the pump flange where the splined shaft is sticking out. I had a 3' piece of 3/4 x 3/4 alum angle that worked well for this. Then I took a 24" long carpenters level and held it up so it was along side (forward) of the angle/straightedge. With the bottom of the level touching the straightedge and the level perfectly vertical, I measured the distance (gap) at the top between the level and the straightedge. I was holding the level with one hand and a tape measure with the other.

Then I just trigged out the angle on a calculator that had "arctan" (aka tan-1) of gap distance/24"

I'm sure that I was accurate to within a 1/4 of a degree which satisfied my inner nerd.

heres some pics of rail kit installs ralph and i have done so you can get an idea.

I suggest you measure 5 to 500 times and cut/drill/grind/etc once. I remember when we did the rail kit in the raspberry, we dropped that motor into the boat and set it on the rails over and over...everytime we put it in, it was at a different angle. 

Frank
The motor plates went down to Azusa with my son on Monday. I'll have him give you a call over the weekend.
Mark--"Sanger Pete"

I was exactly where you are about a year ago.  For some reason I had started to think there was a ton of Calculas (sp?) and black magic voodoo shit in doing this.  As it was, it was damn easy and the folks here on the board and Tommy talked me through this with no drama.  I mounted my rails a touch under the tops of the stringers just cuz I didnt want to muck up a beautiful radius the top of my stringers had.  Go for it and we're all here to help

What size bolts do you guys use for through bolting the rails? I was thinking 1/2". Also should the holes through the rails be the same size, or do you oversize by say 1/16"?

Frank

X2 with what Glenn said.  I went with 5 3/8" bolts per side.  Likely to rip the stringers out before you shear those bolts.

What spacing do you go between the bolts on the rails?

space them evenly

also, use stringer washers and make sure you use a flat bar on the outside of the stringer.

too many times i have seen regular washers on the outside of the stringer and thats it...and they are sunken into the stringer over time. my southwind is done this way and this winter i will be pulling the motor out to fix it.