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Posts: 61
Location: Avilla, IN | Last Fall I picked up a 2022 Alumacraft Competitor 175CS with a Honda 150. Motor has a SS prop, but I feel the performance is not quite there. Can anyone give me recommendations on who may be familiar with an Alumacraft/Honda combo. I have no problem getting a different prop if that will increase performance. Thanks!!
Edited by Duke1 4/17/2023 8:47 AM
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Posts: 296
| What prop do you have? Pitch/diameter/number of blades? What performance are you looking to improve? Holeshot, topend, mid range?
I repowered a 620 with a 250 Honda and will be starting this journey soon. I chose a 19” 3 blade because I’m propping mine for long range multi night camping trips. |
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Posts: 61
Location: Avilla, IN | Number on the prop is S 3 X 153/8 X 18R. It is a SS Honda prop. Hole shot is great, looking to improve top end if possible. Just me in the boat I can hit 45MPH....2 guys 42-43. Seen plenty of posts from guys with 150HP motors on larger boats hitting 50MPH. Just looking for some advice or a reputable company to contact so i can get pointed in the right direction. Thanks |
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Posts: 296
| Not sure what max RPM you are seeing but that engine has a 2.14:1 gear ratio. I plugged those into the Merc calculator.
45mph at 6000(max rpm per Honda) 18” prop yields 6% slip
43mph at 6000 18” prop yields 10% slip
Your loaded slip number would get you to 48mph with a 20” prop (provided you get 6000 RPM)
Your solo slip number would get you to 50mph with a 20” prop at 6000 RPM
Theoretical max for a 19” is 50mph and 20” is 53mp
Gonna be tough to get 50 out of that combo I suspect.
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Posts: 3480
Location: Elk River, Minnesota | Hiya!!
A few questions are rumbling in my mind. First, what are your RPMs? Second question, what bolt hole is the motor mounted in? My gut instinct says the motor will be one bolt hole up off the transom as that was standard set up for overall handling and performance with an aluminum or the stock equivalent steel prop. It definitely leaves some room to improve.
I would also be wondering about is trim angle...at full throttle how far do you feel you are able to go with trim before the prop either blows out or the boat begins to porpoise? I would never want to assume improper trim on the operator part so I will respond under the premise of highest possible trim angle while underway.
Did a little digging on the Honda website...they don't list a prop in the specific size you listed, but they are also listing aftermarket props (Solas, Turbo) and the prop design can make a huge difference in performance as well. I'd be curious to see a picture of your prop which could be another indicator of where things are at currently.
So...what to consider. First, If you are considering a different propeller, I think I'd try to sway you into looking for a prop that has a higher amount of rake built in the design. Something along the lines of a mercury tempest plus. Looking at the diameter of your prop, you could potentially lower the diameter by an inch, and increase the pitch of the prop to a 20. With a higher rake, higher pitch and smaller diameter, you should be close in overall rpms to where you are at now or possibly a touch lower. Now...that being said, you can gain some of those RPM's back by lifting the motor off the transom another bolt hole or two.
These changes will help lift the entire boat out of the water more (higher rake, more bow lift), you'll have less lower unit in the water which decreases drag, and you will possibly obtain a slip number in the single digits. The ideal set up would allow you to keep the bow trimmed while taking a moderate turn, but a tighter turn will cause the prop to ventilate unless you trim down a touch. There is nothing to worry about with having the motor in a higher position off the transom as the water intake on the motor is designed to still be under water at the highest position. And....as the boat passes over the water, it is displacing water which then fills in as soon as the boat passes over it, so the water is actually higher on the lower unit than what you may anticipate. Standard position of the anti ventilation plate is even with the bottom of the transom, but it can be above the transom for that very reason. With a good stainless prop, it is a non issue.
The design of your boat is not one for speed, but getting another 3 to 4 mph out of the boat is definitely possible in my humble opinion. No matter what you try, there is always a compromise going on. Speed compromises handling to some extent, and vice versa. The key is finding a balance that works best for what you want the boat to do in the conditions you find yourself in.
I'm actually back to playing with some props on my rig now as I've found myself running in rougher conditions where the motor is around the 3000 rpm mark. It's enough to have the boat on plane, but it is right on the verge of where vent holes become a problem. I'm running an Etec 150 with a Raker propeller 14-1/2 x 20. I can hit 52 with a low tank of gas (my tank is up front....2003 ranger 617) which does not help much, but it is really steady for fishing up front, which is a plus.
If you are in the northern twin cities area at all, we could touch base around here and take the rig for a spin sometime as well...
Steve |
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Posts: 639
Location: Duluth | Duke1 - 4/17/2023 8:46 AM
Last Fall I picked up a 2022 Alumacraft Competitor 175CS with a Honda 150. Motor has a SS prop, but I feel the performance is not quite there. Can anyone give me recommendations on who may be familiar with an Alumacraft/Honda combo. I have no problem getting a different prop if that will increase performance. Thanks!!
Honestly, call Midwest Prop out of Sauk Rapids or General Propller in Bradenton Florida. Likely can't find a prop out of the box that will get you what you want, but these guys can tune your existing or a new prop to your needs. But it will be right!
I say this because prop games get expensive quick and there's a lot of "information" out there that doesn't come from people that do this work for a living. |
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Posts: 61
Location: Avilla, IN | I spoke with Prop MD out of Plymouth Minnesota and will be trying a different prop this weekend. I'll post my results. |
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Posts: 639
Location: Duluth | Smart, I have used them as well. |
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| Received prop#1 yesterday from Prop MD (14.25x21). Installed the prop after work and headed to the lake. Calm and low50’s. At WOT and trimmed all the way I hit 47@ 5300. Trolling speed went from 2.7 to 3.2. Sent that prop back today. I will ask their recommendation Monday morning……..14.75x19 or 14.75x20?? Thoughts anyone? |
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Posts: 61
Location: Avilla, IN | Prop was Michigan Ballistic |
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Posts: 3480
Location: Elk River, Minnesota | 19. and...if you can stay with the 14 1/4 even better...
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Posts: 61
Location: Avilla, IN | After speaking with Power Tech and Prop MD at length, along with trying 1 prop the conclusion is my original prop is my best option. |
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| Update on this dated topic! Ended up raising my motor 1 notch, did not help with top end speed but seemed to help slightly with my porpoising issue. I also had a water pressure gauge installed when the motor was raised. Motor does not cavitate and holds perfectly fine on sharp turns. My cavitation plate is not visible when running at cruising speed. I believe I can raise my motor once more to the last available hole. Boat does porpoise with 2nd person in back of boat, or if I do not trim down after running at top speed. The amount of resistance I’ve met from marinas/boat dealers has been beyond frustrating. Contacted 4 places about raising the motor to the bottom hole. 2 flat out told me they wouldn’t with 1 of them trying to make me feel an idiot. One of the 4 agreed to look at it and get back to me. Just received his analysis earlier today. Honda recommends all motors have the cavitation plate set even with the bottom of the hull. They strongly suggest I LOWER the motor back 1 notch……LOL. He then said after consulting with his service techs the porpoising issue is probably due to a hull defect and I need to contact Alumacraft to rectify the situation. He mentioned all their motors are set low as possible….and mentioned possible liability. My Honda 150 still has 3 years warranty, are their issues for raising the motor?? |
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