SSM V drive question
 

what makes an SSV a surface drive? or better yet what keeps it from being able to have negative trim? is it the trim cylinders only going so far negative or is it in the gimabl housing? i have a friend who has a 38 flat deck that has #5's on it and it takes forever and day to get up on plane.and when getting on plane the bow is so high up it is almost impossible to see over the bow and if it is a busy day on the water its rididculous. the plan is to weld an aluminum plate to the extension box that is machined at an angle so it has negative trim. basically It is an inch at the top and a 1/4 inch at the bottom. i think there would have be an easier solution than that to come to make negative trim? any ideas?

What is he running for props and drive height ? Many guys with 4's, 5's get on plane fairly easy when they get the right props and height by adding or taking out spacers

26 pitch 5 blade herrings

needs more diameter in props or put a one inch spacer between upper and lower .

The drive height if i remember correctly the prop shaft was 1 inch above the bottom on a 12 inch extension box

You can't just drop the tabs when getting up on plane? The 6's on my OL are roughly 2.5" above the bottom and dropping the tabs (380's) way down while coming out of the hole makes a world of difference.

I forgot to mention that is with the tabs all the way down. the 300s planes

1" spacer and 17.5" dia props should help quite a bit

If you change the angle of the extension box versus transom, the motor will need to be moved also. The engine coupler must be parallel to the extension box input flange or you will get a vibration in the drive line. Possibly grenade a universal joint... The motor and boxes can be offset, just keep in mind the driveshaft angle will get very steep if you tilt the motor and box at the same time. I was told 10 degrees was the max on driveshaft angles, I have seen more but that was the recommendation to me.
I had to cut my extension boxes apart and mill the flanges to match my transom then weld everything back together to get the angles correct.

my 90 MPH model with #5s never had a problem getting out of the hole....drives were set at neutral and tabs down, 16.5 inch diameter 4 blade cleavers...out like a rocket...hardly raised the nose

Won't damage the drive plate, the only thing affected maybe the trans output bearing.

5 blade, 4 blade, 2" spacers... none of those made any real difference until I got a set of props that had over .100 in cup.
cupping grabs water and prevents the burnout.

I've been preaching props for a couple years now, in regards to the older SSM stuff. I've tried ALOT of props on my boat with SSM IV's in the past 4 years.

18x28 three blade mercs. Planed decent. 4000RPM and came over fairly soon.

16 7/8x27 four blade mercs. Planed AWESOME. 2800RPM and layed right over like a ski boat.

17x29 Four Blade mercs. 5000RPM and have a beer. 1/2 mile to lay over.

16.75 x 28 four blade mercs with rounded ears. Planed awesome. 3000RPM layed right over like ski boat.

16.5 x29 Four blades mercs. Simply wouldnt plane at all. Total fail.

16.5 x 28 five blades. Planed awesome. 2800RPM layed right over.

17.5x32 3 blade hoss round ears. 3800RPM, took a while, but decent.

So, I've tried 7 sets of props on my boat. You know what I learned, not a fuking thing. What I mean by that, is with these old SSM mercury props, on these #4 and #5 drives, nothing makes sense. Textbook says, more blades, more diameter,spacers, better planing. In the real world, that wasnt always the case. These old props, are nothing like a bravo style prop. They differ so much from pitch, to blade area, to cupping, and so on. I gave up on what the textbook stuff told me, and bought and sold alot of props trying to find a good set. Ive had several of these sets of props scanned on a prop scan machine. The common denominator that the good planing props had, was a high cupping amount. the bad planing amount, a low cupping amount. Some of the props were so far off in blade to blade pitch it was nuts. Thats just planing talk, not even getting into cruise, speed, and handling.

My advice, before you go chasing ghosts, try a GOOD set of props. They are hard to find these days without going with a new set of CNC mercurys or Herings. Much of the old SSM 15* cleavers have been molested quite a bit.

Ive been told I`ll never get on plane with 4 blades, WRONG!

The horizontal numbers at the right (.100 .105 ..etc ..) thats the cup. This props works great!
Most of the other props that I`ve tried (even 5 blades) had cuppping in the .040 range and those would not even get on plane at all .



http://33outlaw.zenfolio.com/img/s2/...63030030-3.jpg

I see some vertical numbers on the left if that'll do. :party-smiley-004:

thats what I meant to say lol