COMPETITOR 205 TILLER w/ Yamaha 115hp SHO Engine Height and Prop?

Interested to hear what hole you have your 115 SHO mounted in and what prop your running.

Right now I am running a 13 X 17 3 blade Yamaha aluminum prop and my motor is mounted in the second from the top hole.

My 2 tests were as follows :

1) Just me, full tank of gas, full livewell , 4 31-series batteries. I got 39.5 @ 6250 – 6300 rpm with full trim. Cornering prop blows out very easily

2) First trip I had 3 adults, 2 70 labs, full gear, full livewell, full gas tank. I got around 37 pretty consistently depending on water / wind conditions. I think it concerning the weight I was carrying on our 4 day weekend this rig is pretty fuel efficient. I put almost 150 miles on the boat and came home with an 1/8th of tank of fuel!!!

I feel like the motor needs to be raised up 1 hole, this was my first run after the initial 2 hours, full trim and cruising around 30 mph.

Raising the motor will probably make the blow out worse. I would wait till break in is done and test a few props first.

I always ask the same questions about people swapping props or engine mount locations.

-What is the specific issue with the current set-up?

-What are you trying to achieve by swapping things?

I agree with the above idea about getting through your break in period before moving the motor. I’d probably wait that long to try and swap props too. Get a feel for the boat and how it handles over a longer period of time. If the objectives are at all related to fuel efficiency or speed, I’d stop right there. A 20′ boat with a 115hp is never going to be a speed demon and will eat some gas running in the mid 30s with that kind of weight. You can throw a lot of money at props and not be able to defeat physics. If your issues are related to planing speed or visibility that’s where prop changes can make a measurable difference.

Best of luck, sounds like a sweet rig.

Hi Guys,

Thanks so much for the input! I’m pretty happy with the performance and mileage. I figure 150+ plus miles on one tank of fuel is pretty good with the weight we were carrying!

I was just thinking that if the motor is plowing the boat will be even more efficient with the motor at the proper height. I got 12 or 15 hours on her now.

OK, So here’s the results of my 13 x 17 4 Blade Nemesis test.

1) Much less steering torque, not that the 3 blade had much. LOVE IT!

2) Ride change has a little more bow lift as the water seems to be coming out the of the side of boat closer to the driver, it appears to be a couple feet behind mid ship. So I’m getting more stern lift, still can’t see cavitation plate though.

3) I dropped 500 to 800 rpm. I could get to 37 – 39 mph @ 6300 rpm and now I’m really having to trim high to break 5300.. max I could get to was 35.5 mph @ 5600 rpm in calm water and with a chop I could bounce between 36 – 37 mph (touched 38.5 once) @ 5700 – 5800 with max amount of trim, was right on the edge of blow out.

4) Planing was slower not terrible but slower than the 3 blade, You can feel when the prop bites because the boat jumps forward and accelerates.

I’m thinking a 15 4-blade aluminum or a 16 pitch stainless would be about perfect, also thinking motor needs to come up 1 hole.

I really could use some guidance from someone experienced with the 205 Competitor Tiller and Yamaha 115 hp SHO. I’m not trying to tweak the last mph out of this rig, just trying to get it to run like this with out having to driver like I stole it LOL!

Any suggestions would be GREATLY APPRECIATED!

You mentioned you’re close to blowing out? If that’s the case raising the engine is more than likely not the answer. The closer you get the prop to the surface the more likely you will be to blow out. There’s a Merc BHB for a 115 ProXS with CT gearcase on that boat. The motor was mounted in the 2nd hole, and they were running a 19 Black Max(aluminum 3 blade). Max speed was 40@6100RPM’s with full fuel, 2 people, 4 batteries and probably a fairly light load for gear weight. It sounds to me like you’re probably running pretty close to what you’ll get out of it unless a stainless prop can squeeze a little extra out of it. Stainless will keep you hooked up better at the top of your trim range.

Thanks hillhiker!

Good point, if it’s blowing out at max trim it’ll be worse when I raise it. I think probably a 4 blade 16 pitch would put me right where we should be around that 6000. Motor is rated for 6300 max rpm but max HP is hit at 5500 according to the documentation.

I was nervous to try a SS 4 Blade, I’m gonna look for a 16 pitch 4 blade aluminum, I’ll loose to much speed from a 15 I think.

If top speed is a big concern I don’t think you’ll run faster with a aluminum 4 blade. You may be able to get some better hole shot, but that will be partly due to just dropping in pitch. That boat I described above was tested with a 4 blade aluminum as well, and only ran 36@ 6200 with a 17 spitfire. Nothing else was changed on the set up. I’ve found with “under powered” boats the larger diameter, and wide blades tend to carry the boat better. Keep in mind most of the testing I do is done with merc props. Yamaha props may run a bit different…

Hi hillhiker,

Top speed is not a big concern, I get 36-37 fully trimmed but I’m no where near 6300 with the 17 spitfire I’m at 5300 to 5600 max. So I think a stainless 4 blade @ a 16 pitch might be the ticket.

Should bring my rpms up a bit, give me a little more bite when getting on plane and hopefully keep the speed close to what it’s at now.

What ya think?