Prop Suggestions for Yamaha 90?

T

Tortuga

New member
I've decided to do my part for the economy and buy a new engine. Just put money down on a new Yamaha 90 EFI. I'm hoping to reuse my existing Yamaha gauge and key control/ shifter to save a few dollars.

So... what prop is best for a 22 Cruiser ('94)? I've found a wonderful discussion on Honda props for the 22 and Yamaha props for the 25, but nothing specific to Yamaha props for the 22.

Any suggestions as to size, pitch, aluminum v stainless would be greatly appreciated. I run the boat out of Ventura CA -- so I'm at sea level -- and in moderate chop most of the time... but there are those 5:00 am trips across a glassy channel to the Islands... (course then there's hell to pay on the way home with the afternoon winds and following seas...)

Cheers!

Matt
 
Matt-

When I changed over to my new 2005 EFI Yamaha on my CD-22 '87 Cruiser, they set me up with a 17 inch pitch prop.

It was fine, or at least OK, in the beginning, but as the boat grows heavier with all the stuff one adds with time. I think it's a bit too tall.

Originally, the boat would wind up to a max of about 5400 rpm, but now is down to about 5100-5200, not that I run it at WOT very much.

A 15" pitch prop would probably be better. Each inch of pitch equals about 200 rpm at the top end (an approximation, since many other variables, including gear ratios, enter into the equation.)

I've actually have and have run a 15 inch pitch prop, a four bladed Solas brand (used also by Hondas) that yields about 5500 rpm, but I don't keep it on the motor all the time because of all of the driftwood we have here on the lake.

I've got two of the 17's and the one 15 and much prefer it for power, hole shot, and heavy loads, but have chosen to ding up the 17's first instead. The 15 would be easier and better for the engine, however (less lugging).

Hope this helps.

Joe. :teeth :thup
 
I have twin 40 Yamaha's on my 22 cruiser...so I would not be of any help... Roger...(Sea Hawk) just had his Honda 90 re-proped..actually bought new props... I am thinking I will try that Prop Shop in Ventura and see what they charge to re-pitch mine... rather than buying new...

Joel
SEA3PO
 
Yes that is the place..... my Yamaha 40 props are dinged up some and are sure to be a bit out of shape anyhow...so repitching them probably would help....as it is now...I can only turn 4800 rpm loaded....wide open..I think I should be able to turn 5600 wide open... But I also hate to mess up my fuel mileage...it's pretty good....just over 4 miles per

Joel
SEA3PO
 
don't know if this helps but i put a 14 1/4 x15 ss on my new 90 etec and its too much prop for my 22 (max's @4400 and should be more like 5200). I may be running it a bit too low but my guess is that you would certainly not be happy with anything over 15p.

Chris
 
cemiii":15yiwerr said:
don't know if this helps but i put a 14 1/4 x15 ss on my new 90 etec and its too much prop for my 22 (max's @4400 and should be more like 5200). I may be running it a bit too low but my guess is that you would certainly not be happy with anything over 15p.

Chris
Click to expand...

Chris- With a 2:1 gear ratio, a 15" pitch prop sounds about right (very common choice), but that 14.5" diameter may be a bit much, not allowing much slip at all. Usually motors in this HP range with a CD-22 use a 13.25-13.75 diameter prop.

Slippage is considered OK in an approximate range of 10-15%.

Did an Evinrude dealer recommend that large a prop?

In heavily loaded CD-22's (or those used at higher altitudes) a 14" pitch prop is often desirable to get the WOT RPM right, but very few 14" pitch props are made, so sometimes a 15" pitch prop is re-pitched a bit.

At Eagle Lake, the 4200 feet of elevation would rob you also of 12% of your hp! (About 9-10 hp!)

(3% for every 1000 feet over the first 1000, which don't seem to make a big difference, although I'm sure there's some.)

Joe. :teeth :thup
 
My initial dealer prop was a 17 pitch. Chris (Rana Verde) strongly recommended the 15 pitch on my EFI Yamaha. I bought one and retired the dealer prop as a spare. Chris was absolutely on target. Much better hole shot, much closer to 5k WOT, and just plain better across the range.

I had intended to re-pitch the 17 down to 15" but never got around to it.

Don


Currently boatless
 
Joe, here's my dilemna. I bought a long shaft 08 etec 90. The long shaft only comes with the v6-v8 gearcase. I thought getting the powerhead high was the way to go (miscalc) The large gearcase only uses the big props 14.25" and larger. 14.25x 15p was the lowest ss prop I could find stock.

I do have an aluminum 15x 13 that I have not tried yet though the extra diameter may offset some of my pitch gain. It's a tiny bit dinged on the edges so I may have them redo and even try to lower the pitch a bit more if possible.

At full throttle and any trim level I throw a pretty large hump out back. I had a prop guru tell me that's a sure sign I probably need to raise the motor another 2-3" up which would involve adding another plate. I'm contemplating doing this but it's a big job so I want to fully explore all my prop options first. A new gearcase for the new motor is just kind of financially out of the question right now. My permatrim is also probably a big drag if I'm too deep.

Those figures were at 4200' so the next test job is the 13p prop on the Sac River.

chris
 
Chris, you can use smaller diameter props, but it will not be as effecient. Larger props are more effecient. (This is one reason I choose Suzuki for the Tom Cat, since they can swing an inch bigger prop than most other 150 motors) Generally you want the largest prop, you can swing. Basics--increasing the diameter of the prop one inch is the same as increasing the pitch 2 to 3". This translates into 400 to 600 RPM decrease at the top end by going from 13.5 inch to 14.5" prop.

At this point, the gear ratio does not make a lot of difference. What is the issue is the Wide open throttle performance of the engine. You should be able to get close to 5850 RPM with that engine. Also remember that every 3700 feet, you need to drop pitch 2" because you loose about 10 to 12% of the HP of the engine.

The third factor in your boat is that the engine is sitting too low, combined with the permatrim (which should run right on the surface of the water. If your engine is a 5" longer shaft than the boat was designed for--you either have to put on a jack plate which will give you the 5" lift, or raise the transom 5".

An aluminum prop will "flex" more than a SS prop, and that can account for as much as about 1/2" pitch. You will probably gain a max of 500 RPM at sea level with the 13" prop, which will bring you up to about 4900--maybe a bit more since you are at sea level. At 4200 feet you will probably want to run a 15 x 11" prop. ProTech will be able to get this prop, but also there are props with less cup--more "power" props, often no cup and no rake, which are used for houseboats etc.

All boats will have slipage of the prop--10% is low in my experience--but this is a good thing. On my C Dory 25, I had close to 40%--better with some fooling around--but still not ideal.
 
Thanks guys, I've witten to pro tech on this. No reply yet. There are lots of under 15p props in the 14 dia and less small gearcase size, but not many for the big gear case that runs a bigger shaft size (1 inch, i believe). I am also looking into other props that are made to accept Flo-torque hubs that I may be able to adapt a smaller diameter.

I've already got well over 5" lift on a big CMC jack plate that is backed by a very large 3/8" aluminum plate and big alluminum backers to beef up the transom.(see album) The anti-cav plate is now dead on level with the bottom of the boat but several inches rear of where it would be on the transom only. Back there, I've been told I need to be a couple inches higher than level.

I've already machined another 3/4" 6052 alum plate to mount the motor 3.5 inches higher on the plate. If that should prove too high, I have 5" of drop in the jack plate to fine tune it. I kind of dread adding even more rear weight and remounting so I'm still playing around with prop options. One serious issue was trailer tongue weight but the new trailer with bunks rather than rollers should take more adjustment.

It really does jump out of the hole though with the big prop. I'm literally on plane in a few seconds. At 3800 rpm at 4200feet she cruised nicely at 21.7mph gps but there was almost nothing in performance left from 38 to wot. I know i'm getting much better mpg, quieter, no smoke higher charging and instant starting but so far I'm getting no better top end than the old Johnson 70.

Chris
 
The general rule of thumb is back 1" up 1/2"--of course you want to be sure that the water pickup point is always submerged.

Of course the question remains, how much extra bracing will be necessary as you raise the motor (I have loked at your photos--I assume that there is equal support below the splashwell. There is a lot of leverage on the jackplate, as you raise it more than 5".

I guess another question is how does the boat sit level? You mention excess weight there. I noted in the past you had two kickers, I assume only one now.

The 90 should be giving you significantly more speed when you prop it correctly.

One other question--no trim tabs?

I think that with the larger foot and high motor you are getting into some really non standard dynamics aft--but I stick with the lower pitch prop--and Power tech will have some available---but not cheap. I contacted them before this summer--and they made suggestions--I chose to ignore them, and worked out a good enough solution with trim tabs/permatrims/mounting--but for Powell, I probably should go down to an 11" pitch prop.,...
 
When you buy your new motor the dealer should give you a couple props to try. Load the boat the way you intend to use it and try a couple. The dealer you buy the motor from should do this with no problem. Just remember should you be getting a stainless prop use stainless to test with.
 
Bob, thanks again, I never really had 3 motors on there, just hung the old tiny 2 stroke 15 to show the wild comparative size difference compared to the new 4 stroke 10.

The big plate on the back of the boat covers all the way down to the drain plug. It's hard to see because it's painted to match the bottom gel color. There is an 6x14 backer under the splaswell. I hit a rockpile at Eagle lake at 20 mph. I didn't want to look back for fear there was likely no transom or motors or at least prop left.

But I can see no damage except for the big blems on the Skeggard and a minor prop scratch. I was fortunate to have a skeggard on. But, it looks like the transom is fairly strong, via unintentional stress testing.

I don't have trim tabs and don't feel I really need them right now. I get great up down trim from the permatrim, and usually a half step move by a passenger or my self levels her laterally. As mentioned, she plains instantly without tabs. Sits fine in the water, pretty much parallel to the bottom gel coat line, even with full tanks and a 6 gal kicker tank.

It looks like a Mercury Black Diamond aluminum prop can be had in 16x11p and looks like it may take an XHS100 etec hub kit. Trying to confirm this. Another $150 experiment. I have a brand new power tech prop now but it's 15P and the lowest fitting pitch prop in their catalog.

Really sorry I hijacked Matt's thread. :oops: I hope he's gotten his answer. I think he has, but if anyone has anything else on yami-propping
please jump back in here.

I bought the motor used from a dealer out of FL who put it on a guys pontoon boat for about 20 hours and he forced the dealer to swap it for a short shaft motor. Now I know why, he probably couldn't prop it right either.

Chris
 
cemiii":1d38sq23 said:
... Really sorry I hijacked Matt's thread....
Click to expand...

Not at all... I got more information than I anticipated -- many really good suggestions. Sometimes its better to sit back and listen... and this was one of those times. Thanks to everyone. When I get my new motor mounted and test some props I'll post the results.

Matt
 
I noted the difference in the size of the motors--very dramatic! I figured that you had the bracing well covered from what I could see on the jack plate.

The difference between the trim tabs and the Permatrim is that side to side trim can be altered, and I have always brought the boat up to a level ride, than brought the outboard/I/O leg so it was pushing straight ahead--of course the Permatrim can alter all of this dynamic. You are correct, that the C Dory does not really need trim tabs, and I didn't have them on my 22, but they certainly do make a large difference without the Permatrim. (I have both on my 25--and adding the Permatrim made a definate difference, with more stern lift.).

My impression in talking with the Power Tech folks was that they could come up with props other than what were in the catalogue. When you go to a 16" prop, it will drop the RPM several hundred RPM--and the 11" will increase it several hundred--hard to know what the net effect will be, but it should be a lot of torque start up--not something which you seem to need. Bottom line, if you are runing at several different elevations; several different prop pitches will pay off. We had 17", 15" and 13" for the 90 on our 22--
 
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