Kicker shaft length on CD-22?

wesshaw · Posted: Mon Feb 02, 2009 5:33 pm Post subject: Kicker shaft length on CD-22?

With a 'new to me' last fall C-Dory 1991 Cruiser, I'm developing my work list for the "coming spring" (ha!) here on the DownEast Maine coast..... She came with a newer 90 hp Yamaha and an old 9.9 Suzuki kicker. With some use this fall and early winter the 9.9 seems to run OK but I do have an almost new 9.9 Merc elec. start that I'm thinking of replacing the old Suzuki with.
My question is on shaft length vs. transom height? The C-Dory transom is exactly 20". The old Suzuki presently on her measures 27.5" from the bracket rest to ctr. of prop. (I'm going to call it a long shaft...) The almost new Merc 9.9 measures 23" from bracket rest to center of prop (? short shaft?). This will put the center of prop a good 3" below the bottom of the C-Dory hull and the cavitation plate just below the bottom of the hull. I kind of realize that a "long shaft" 9.9 would be perhaps more efficient BUT all I'm looking at this kicker for is a back-up to get in with if I have problems with the 90 hp.... ——Any thoughts/experiences from any of the great minds on this site would be most appreciated! (You were a great help in November in getting my Wallas stove repaired...)
Many thanks, Wes Shaw

Wandering Sagebrush · Posted: Mon Feb 02, 2009 5:49 pm Post subject: Kicker

Hi there Downeaster,

My guess is that the Merc will be fine, but hang it on the transom and check for yourself. If the top of the prop clears the bottom of the hull, you will probably have no problems with it sucking air. Worst case is you would put the Suzuki back on if you didn't like it.

Regards,

Steve

wesshaw · Posted: Mon Feb 02, 2009 5:56 pm Post subject: Re. Kicker....

Thanks Steve... That was/is my plan but can't attempt it yet until about 4 solid inches of ice and 2 feet of compressed snow melt.... ( : >) Wes

cemiii · Posted: Mon Feb 02, 2009 9:35 pm Post subject:

On my 22, I have hung a short shaft 15" kicker on the transom with no problems or cavitation.

I have hung a long shaft 20" on the transom with no problems or cavitation.

I have put a long shaft on a jack plate probably vertically about 4-5 inches above the bottom of the boat, but several inches back with no problems or cavitation all the way up to full throttle. (the purpose of this was to move it to the port side where the arm is tough to clear)

In my opinion, you will not have a problem right on the transom so long as your water pump stays wet. If you should, moving it back 3-4 inches on an inexpensive fixed jack plate will almost certainly resolve the issue.

Chris

thataway · Posted: Mon Feb 02, 2009 11:12 pm Post subject:

The long shaft will be slightly more effecient--and if you try reverse with the shorter shaft, it may not work as well, since there is more prop wash against the transom. I have used only short shaft Kickers, but on brackets, so that the engine can be lowered appropriately into the water, and then pulled up to completely clear when the boat is on a plane.

In heavy seas, the prop on the kicker may tend to pull out of the water and cavitate was the stern lifts.

The newer Merc may be heavier than the Suzuki.