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AnthonySS
07-02-2001, 02:51 PM
More STV Transom Height Tech,

Dear STV Company,

I Just got back form 6 days at the lake it was great weather and great times. I still did not get out in the STV. As I was putting on the SM, I cracked the water pipe guide. Oh well maybe next weekend!

However I did get a chance too due some transom height measurements and here is what I discovered. The present transom height (from the bottom of the pad to u/s of clamp bracket is measured at 29 ¼". This sets the prop Shaft c/l to approximately ½" above the pad and puts me in the 27-30" transom height as recommended for the SM.

Taking into consideration RT's middle hole on the clamp bracket theory would set transom height to 30 ½". Even though I am on 5 ½" of Set back, this still puts me at least 1 ¼" too low.

Unfortunately, I did not get any seat time to determine RT's theory effective on my STV. So once I get my SM back on the motor, the engine is getting jacked in the range of 1-1.5".

Hey guys, If your rig is in the driveway, get out a reliable straight edge, a measuring tape, place straight edge on the pad (get your girlys to help) and measure from the top side of the straight edge to the U/S of clamp bracket, and let me know how your transom height measures up for your "sweet spot" set up!

Looking forward to hearing your replies!

Sincerely,

AnthonySS

Way2Fast
07-02-2001, 04:02 PM
Why involve the motor clamp bracket into the measuring process at all? Just measure the height of the prop shaft center in relation to the bottom of the pad. (With both pad and prop shaft being parallel of course). This measurement will be consistant regardless of setback, midsection length, etc. I run mine no less than 3/4" above. You can go up till you start to loose water pressure or handling. The "sweet spot" has to be found by trial and error, not by what Merc suggests as the proper height to run a SM. Rich, 2001 drag/RR center steer

AnthonySS
07-02-2001, 06:45 PM
RICH,

I completely agree that Sweet spots are found by trial and error.

Just to bring you up to speed..I have had many questions about setup of the SM drive after using a Bob's Alli-mod for years. Unfortunately the SM did not net instant satisfaction like the BOB's. So my first check was to see if I was in the 27-30" transom height range and then start deducting from there.

Besides adding another variable like noting the transom height, just makes the sport more interesting in my opinion.

Thanks for your comments,

Sincerely,

AnthonySS

Euroski
07-02-2001, 07:44 PM
Anthony sorry you didn't get to have some fun. Ran my new lab cleaver(14.5x30) twice but still haven't found the correct place to put the prop shaft. The first time out had it the same as where the ET28 runs the best 3/4inch up. Just didn't feel good, boat felt "glued" to the water and wouldn't air out even at 90! Water pressure was 10+ under 5000 and over 20 above that. This past Sunday I raised it to 1-1/8inch above the pad. Felt very good but water pressure was to low for my preference. Under 5000 only had 6psi and maxed out at 13-14. Merc wants at least 12psi! Also engine temperature was up to about 165 from normally 150. Next time out I am going back to 1 inch and see what happens. Now for that measurement with the p/s 1-1/8inch up I get 29.5inch.

Raceman
07-03-2001, 09:19 PM
Why'd you let a little thing like the tube guide stop you? It's just a guide, the seal holds the pressure. C'mon now, stick it in the water and let us know.

ProComp
07-05-2001, 11:04 PM
Spend the past several days playing with set up. Didn't get a chance to measure but I am sure I ended up with the propshaft centerline about an inch above the bottom of the boat. Bouncing is pretty much gone. Running 92 mph on speedo with two people and a consistant 85-87 with 3 people. Pulled several skiers, tubes and dual tubes all with a modified 29 OMC prop. Wife loves the fact there is no wake with this boat which is a good thing as the 3 seater was a hard sell. My two cents.

Brad
92 STV ProComp
89 200 Merc with Sportmaster

AnthonySS
07-06-2001, 11:46 AM
SOUNDS great BRAD,

I would say the bouncing is gone due to seat time!

Sincerely,

AnthonySS

ProComp
07-06-2001, 12:01 PM
Anthony, in all honesty, I think it is the engine height. Better angle of attack and more rear lift if bringing the boat out of the water. Before it use to feel like the back of the boat was actually getting sucked down. Now it seems like it is flying or aired out. Works real nice in the chop or into the wind especially.

Firestarter
07-06-2001, 12:11 PM
I agree, engine height is key, The boat handles better in all ways with more engine height. Brad you are absolutly correct in that all of a sudden the boat feels free. It to me is a more secure feeling, and it is true about rough water, the boat runs a lot flatter when setup like this. Also it is safer to run the boat into the wind than down wind. If you are going 100 down wind and you have a 20 mph wind the boat is hydrodynamiclly running 100, but aerodynamically running 80. If you happen to hit a still spot it can get a mouth full of air and take you for a ride. Into the wind you have already compensated and if you loose your head wind you just loose lift.

Glad you are getting dialed in.

RT