Yamato 80 Transom Height

[Richard Russo]

Just about have my 30+ year old A-B Racecraft runabout ready for the water after being dry since the early 80`s. I was wondering what is the typical transom height for this engine i.e. holding a tape on the back side of the transom measuring from the bottom to the top? What is the typical height of the prop shaft below the bottom of the boat? I would think this hull would handle this engine ok since I used to run a Merc in BSR years ago. Any tips would be greatly appreciated.

[Jack Stotts]

Transom Height

The rule book, page 6, within stock safety rules, Safety Rule 4 Engine Mounting Heights mandates that the prop shaft on 20SSH be not higher than 1/2" inch below the bottom. This is measured from the aft end at the center of the shaft. You may want to start out testing with it below that level. Moniter the cooling while finding your final position.

[Richard Russo]

Thanks for the answer, but....

Thats great- that answers 1 of my questions. This runabout has never had a Yamato 80 on it, only an old merc A or B. Saying this, what is the typical height of the actual transom if one were put a Y-80 on it? I don`t know if I`ll have to trim or add to the transom in order to get the proper height. I would like to do this before I get to a race- thanks.

[BP125V]

depends....

on the angle of the transom. the only way to know for sure is to put the engine on.

Bill

[NUT2F]

Richard, Be careful with a small A-B runabout, the 20 motor has more weight and torque than a A or B. I ran a couple A-B runabouts in the 80's with a 20 motor, it's tricky!! If you do it, I would test it before you try nto race it!

[Jeff Brewster 59s]

I ran a Model 80 on an Asr for years and the rest are correct. It is a wild ride that needs treated with respect. The torque is tough with a narrow bottom. It depends on what organization you are racing in for a legal height.
I ran a transom height of 16" until the height restriction in Apba came along and killed the Bsr class. I suggest starting out at 15 1/2" and working from there. Check your rule book first though and good luck.

[Richard Russo]

Thanks!

Thanks for the info guys. I kinda figured that Y-80 would be pretty torquey- Once I test it, that will determine if I race it or not. I`m sure it would be a wild ride. Controlability, handling and safety is paramount. I`m not as young as I used to be.

[STEVE FRENCH]

Give Doc Miller/Rick Morris a call....and Dudley Malone....Lots of knowledge avail there.....

19P

[ddh]

rich sent you pm