Outboard Motor Forums (by brand) > Mercury/Mariner Outboards
Prop question
Sully401:
Hey everyone!
Been doing some light research but figured it was time to ask around as well. I currently own a 99 Mercury force 40hp outboard on my 2001 track PT 175 boat. I bought the boat this summer and really have not done much to it yet. But now that its winter i am looking to try and improve to motor a bit for the 2017 season. Just above the prop on my motor is a sticker that indicates: 13x26 2.00:1
The boat came with two props. the prop i am currently using doesnt actually have a size indication on the inside of it, here is what is reads: 48-81670814 The second prop however has a clear size reading on the inside and states its a 38x14p prop.
With the 38x14p prop i have a pretty good holeshot but not much top end. GPS indicated around 26mph. With the other prop (thats for sure smaller) i have an ok holeshot and get about 28mph.
I have read that done right these 40hp motors can push around 30-35mph and i would obviously love to achieve that. With all of this being said the motor itself does need some attention....she needs a new voltage regulator and possible stator as well and of course, a good carb cleaning as the previous owner said he only used the boat 2-3 times a season.
With motor stuff put aside im just curious what people think i should try for a prop for this season. im looking to achieve the best top end i can get without totally killing my holeshot.
Thanks in advance!
Curt:
Hey Sully!
First off, let's talk about realistic expectations for a 17 ft. aluminum boat with a 40 HP outboard. Assuming that you have power trim and tilt, you can realistically expect to get about 32 MPH out of it under ideal conditions and two people in the boat. Maybe a tiny bit more, but only under perfect conditions.
Now, regarding your props, I'm willing to bet there is a number stamped somewhere on that one prop, but it might be hidden under paint or something. Who knows? But, with regard to the number on that other prop, 38x14 doesn't sound right to me. The 14 does, but the 38 doesn't make sense. The 14 should be the pitch and the other number should be the diameter. Can you check those numbers again and make sure of what they are?
Also, if you have manual trim, and not power trim, you will never get optimal top speed out of the boat, since your outboard will be in a fixed position that will be a compromise between good holeshot and top end speed.
You can also try playing with the height of your outboard by moving it to different holes. Moving it up one set of holes will usually give you pretty drastic changes, but not always positive changes. But be careful not to raise it too high so you don't end up losing water pressure.
Lots to consider here. But remember to keep it realistic in your expectations because MPH cost a lot for a little return on your spend :thumbup:
Sully401:
Thanks for for the reply curt! Yes I am wel aware that I could spend a lot and not get much in return. If I could achieve even 32mph in the boat I would be ecstatic. With that being said. I know my motor needs some attention and this topic specifically is just me asking around for what prop size and diameter would allow my motor to perform at its top end. I attached the photos of the inside of my props that I took. The props do both have serial numbers stamped on the outside but I'm not quite sure if that will help at all. Cheers!
Curt:
Prop diameter and pitch are usually stamped on the outside of the prop itself, not on the hub. So my guess is that you're looking at part numbers for the hubs. These would be unrelated to the prop specs.
The sticker on your motor is probably also unrelated to the prop, related to the lower unit.. possibly the gearcase?
@bullet20dc Do you have any feedback on this one?
Also, I read a post today of a person selling a Tracker 17 footer with a 50 HP Merc 2 stroke, and he is getting 32 MPH from that boat with 2 people and a full load. So the 32 MPH goal with your 49 HP might be unrealistic, but maybe 30 would be attainable with some tweaking of motor height, correct prop, etc.
Jig Man:
You have not stated anything about rpms. Do you have a tachometer? If so what rpms are you turning with each prop?
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