Prop performance update

[1988bomber]

I have a 1988 16' bomber bass boat, 1988 110 v4 evinrude, 13x19 alum. michigan match prop, engine height = prop shaft ~6" below pad. I had problems trimming up much at all before ventilation. Ran ~40 mph @5400 with medium/light load. Many people suggested the 18 pitch raker.<br /><br />---------<br /><br />Heres an update on my situation....<br /><br />I came across a 20 pitch raker for $120, so I figured I'd give it a shot. Well, I can run 47mph at FULL trim at 6000 rpm. This is with 1 man, 2 batteries and a full tank of gas. My rpms increased by 600 from my old 19" alum. because I can trim it up all the way now. My hole shot appears to be about the same (I won't really be able to tell until I get 2 more guys on board). I didn't touch the engine height (prop shaft is about 6" below pad).<br /><br />For an experiment, I filled up both livewells (one front one back ~20 gallons total I guess) to kind of simulate having another person on board. The hole shot was about the same, but I topped out at 45@5800.<br /><br />So, my question is ... what next? My owners manual says 4500-5500 rpm. Is 6000 too much for this older evinrude (1988) ? Should I try to go up in pitch or change engine height? I'm not sure, but I have a feeling that when I get 2 more guys on board and their gear (close to max load), I should be ok with the 20" raker. <br /><br />Any thoughts?<br /><br />Thanks,<br />-88bomber

 

[Jack Shellac]

Re: Prop performance update

Sounds to me like the 20" is just about ideal for your boat. I don't think it's good for the long life of a motor to run it over rated RPM for more than a few minutes at a time, if at all. When you load the boat up, your RPM's will probably drop some, as you expect.

 

[1988bomber]

Re: Prop performance update

Thanks Jack.<br /><br />The thing that bugs me is that I have the ability to raise the engine about 2" which would put my prop shaft at 4" below pad. I have been told that 4" is about right for my boat. Obviously, I would like more top end. But I am worried that my rpms will increase even more and my holeshot will suffer greatly. I guess I could give a 22p raker a try. I guess the only way to get it right is to experiment.

 

[Bondo]

Re: Prop performance update

If you sanded All those Bumps Off the Bottom, You'd Need a 24" raker......

 

[1988bomber]

Re: Prop performance update

bondo,<br /><br /> You really think it would make that much difference in drag if the blisters were repaired? Do you have any experience / expectations with my situation?<br /><br />I just hate to take on that job myself and I'm too stingy to pay someone for it, but if it's holding my boat back that much, I need to do something.