Quote:
Originally Posted by AC2717
Hi Guys.
Looking for some advice. I have a 14 foot Lowe Fishing model aluminum boat with a 25hp mercury on the back. The boat weighs about 660lbs without the motor which is 148lbs and the safety plaque says 5 people or 550lbs for gear and people.
I am about 205lbs, battery is 65lbs 6 gallon fuel jug, fishing gear, and then my fishing partner (my daughter) is 125 lbs. so with the motor we are basically capacity. When my daughter takes the boat out lets just say it moves a little faster without me on it and planes a little better, but I do not think it gets out of the water as much as it should. When just me on the boat i have to stand to get it to plane out somewhat and move a little faster, and when I turn slows down and bow up again, when both on the boat i have to sit up the bow but we are still throwing a wake more than it should
all of the above is at WOT. In all conditions (except with just my daughter on the boat, and even then in watching it does seem like still could see a little help), it just seems like it should be a little more out of the water and then obviously move quicker than it is. add this one: don't even think about touching the trim slows it makes it sit down even more. The engine is in perfect running condition and has been combed over.
The engine and set up from boat maker and mercury calls for a 9 inch pitch to and 11 pitch but we all know they are guidelines for the most part and it has to be application specific. It is a 10 spline prop shaft. Currently there is a 9 pitch on the motor (brand new) and I have put a foil on (SE200) to help it get up out of the water, it helped a little but it seems like the motor is working hard and the boat itself is weighing it down so to speak.
I have pulled as much weight as I can out of the boat already, understand more pitch is more speed but slower hole shot. So do i increase pitch and diameter as well??? How do I test everything out without buying numerous props and being stuck with them?
I have a 11 pitch stainless prop to put on there, but mechanic advised to take it off due to the weight of the prop and the size of the motor and the lower end and shaft taking the extra weight on??
help me out here. thank you
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You could try using this prop sizing calculator, worked perfectly for my Pontoon Barge. Just make sure your not over revving the motor at WOT
https://www.miwheel.com/outboard-pro...zing-analysis/
Or my favorite - bolt more power on the back