Props for Merc 90

Randy,

This doesn't relate directly to Hydrostreams, but if you have time and room on the page to answer my questions, I'd appreciate it a lot. I've been trying to find the ultimate top speed propeller. My motor is a 3 cyl. Mercury 90. The boat is set up so that it doesn't need any additional bow lift, it's rigged for a cleaver. I've tried several propellers, but the best I've found so far is a 13 1/2" x 30" over hub cleaver with very small cup. I have no idea, who manufactured or reworked it. It had Ron Hill stamped on it, but it was clearly modified after Mr. Hill. It had very thin blades and it threw a blade after two seasons. I've been trying to find a replacement for it, but I don't know who reworked it, etc. The hub doesn't look like a Mercury. I have a 14" x 28" over hub Merc Cleaver, which is reworked by the same mystery guy, who did the 30". The 28" works well, it's reworked pretty much the same as 30", but with thicker blades, and it has better acceleration, naturally. The 28" is a very good prop, but I'd still want to have the ultimate top end performer I once had. I've run several other small dia over hub Mercury Cleavers, but never found as good a performer as the 30". Maybe the worst thing I ever did was throw the wounded prop to the lake, because I was so p_____d of demolishing it. Perhaps I could've had made a copy of it based on the two remaining blades.

I've tried several other propellers, too, but I've never found the one. I've tried an old thru-hub Mercury 14" x 30" cleaver, but it's acceleration is very sluggish. It's almost as fast as the over hub 30", but it lacks 2/300 rpms and is very "heavy". The motor can't accelerate at all and the prop requires the ultimate weather. I was told this was the older inline, thru-hub model, which had the bigger blades than the new ones. Haven't tried a new blade thru-hub, but I'll have a chance to test a lab finished one in a couple of weeks. I've also had the blades cut a bit on the old thru-hub to get the prop to perform, but it won't help enough. I've also tried a 14 1/2" x 30" Mercury Cleaver. It's had it's dia cut a bit, but it still had the "fatter" blades compared to 14" Merc Cleaver. This 14 1/2" prop had the same symptoms as the old thru-hub cleaver, it's too "heavy". I've also tried several round ear propellers. The fastest of them was an old Mercury inline chopper, 14" x 26". It ran almost as fast as the Merc 14" x 28" Cleaver, but it cracked a blade, as inline choppers do. The inline chopper didn't have a good acceleration, it was worse than the 28" cleaver, but I was still able to drive the boat with it. It wasn't as heavy as the thru-hub or 14 1/2" cleavers. I can't imagine running a 28" inline cleaver, it would have too much pitch and blade area. Then I've tried a 14" x 27" Hoss Triton, but it wasn't any better than the inline Chopper. Plus, I've tried a Yamaha copy, a 14 1/2" x 26", but it was clearly too big for me.

What do you think? Which Cleavers are the best? Should I stick with small dia Mercury ones, or should I try Mazco's or Spinelli's? Has there been any changes in Mercury Cleavers' blades, like in thru-hub props, that I should know of?

Regards,

Larry

 

Larry,

Sounds like you had an old Mod VP prop that Ron cut down. If your boat is like most of the 90hp powered rigs I've run, it makes sense that it likes the small cup, small blade area cleavers. Cleavers tend to spool up better than choppers and the like. With the limited power, that characteristic is what you need. Too bad you don't have the old "2" blade as Mercury could copy it. For now the new Merc cleavers are different in the metal used and the hub style. They still could make one that worked. I have a small blade area 30 cleaver that might work. It has too much cup for your boat but it could be modified to fit your boat. If you wanted to try it I'd sent it to you. For V6's it's a little light but it would give us a baseline. Other than that, the 14x30 cleaver that was 300 rpm low could be tailored to your rig. It sounds like it's pretty close. I agree that the cleavers are the way to go with your boat. My experience with the 90 has been the cleaver is easier to deal with less compromise, compared to round ears at that power level.

                                                              Hope some of this helps.
                                                              Randy

 

 

Please submit whatever questions you have to IHRTechTalk@yahoo.com.  All questions and answers selected will be displayed on this page as they come in.  Note: though all boaters are welcome, priority may be given to I.H.R. members.  Randy can not be held responsible for any advice given.  Though his information and expertise is second to none, he has no control over what you do with your boat.  It is up to you to boat safely and act responsibly, and his advice is only to be used as a guidance for your high performance boat/motor of which you are the one responsible for the risks involved.

Thanks,
Mark C.

 

[ Home l About I.H.R. l History l Models l Registry l Members' Pictures l Feature Article l Tech Talk ]
[ Literature l Events l Top Guns l Guest Boat l Classifieds l Video Gallery l Racing Corner ]
[ Prop Slippage Program l Animated Videos l Screen Savers l HIN Decoder l Links l Contact Mark ]