Prop size

[FLASH BANG GARY]

Hi,any one help me what prop should have been fitted on my Maxum 2100sc it,s a 4.3L (carb) with a
Alfa 1 leg year is a 2000 not shore of HP it is but I now it's fast 55mph I need to replace the prop as as its got lots stress cracks any help would.
Regards Gary.

[biggerseagar]

Greeting Gary...........There is a process that you go through to figure all this out. You have to load the boat up... yourself and a guest and put the pedal to the metal as we say it over here. At top speed what is your RPM guage saying? Is it within the manufacture's guideline of your engines rpm's should be. example 4500 rpm's or 4200 rpm's at wot. (wide open thottle).The right prop will have your right in there at wot for your rpm's.

Find a prop website and use their guidelines. Your old prop should have two numbers stamped on it for pitch and diameter. Use that as a start. Maybe all your want to do is to get the old prop fixed up. What kind do you have? A aluminium or stainless steel? Take it to a prop shop and they can repair it for you.

Ask yourself a couple of questions....will I pull skiers with this prop or do I what to go fast (sounds like you already have that one dialed in) and go from there.

Good luck and have fun!

Roger

[FLASH BANG GARY]

Originally Posted by biggerseagar

Greeting Gary...........There is a process that you go through to figure all this out. You have to load the boat up... yourself and a guest and put the pedal to the metal as we say it over here. At top speed what is your RPM guage saying? Is it within the manufacture's guideline of your engines rpm's should be. example 4500 rpm's or 4200 rpm's at wot. (wide open thottle).The right prop will have your right in there at wot for your rpm's.

Find a prop website and use their guidelines. Your old prop should have two numbers stamped on it for pitch and diameter. Use that as a start. Maybe all your want to do is to get the old prop fixed up. What kind do you have? A aluminium or stainless steel? Take it to a prop shop and they can repair it for you.

Ask yourself a couple of questions....will I pull skiers with this prop or do I what to go fast (sounds like you already have that one dialed in) and go from there.

Good luck and have fun!

Roger

Hi,Roger
Over in the UK we call it giving it !Some Welly! My problem is that my prop is completely shot it I dare not use it in case it flys off it is stamp on the back 14.5. 20P it is stainless and has 4Blades but I'm not sure
It's the right one,
This may be why it's cracked
I no I had 6 people on board and had it flat out at 55mph not sure what RPH were at so I'm not sure the best way to go .
I do not spend out £400/£500 on a prop and get it wrong they seem to better price in the USA
Regards Gary

[biggerseagar]

I have always had very good luck with Overtons.com website with price and selection.

You are just going to have a find a friend in the prop business to get you started. Some prop shops over here let you try out a prop and either like it or try something else until you get it right. Check around at your marina and see if you can get some free advice from an expert and take it from there.

Roger

[FLASH BANG GARY]

Ok thanks for help.
Regards Gary.

[shrew]

Hi FlashBang Gary, Welcome aboard!! I can respect the delima you're in. As Roger described, that is the easiest way to figure out which direction to go when you have a prop. In your case, here is where I would start. Collect to following information:

1) Diameter of current prop:
2) Pitch of Current Prop:
3) Number of Blades on current prop:
4) Weight of boat:
5) Length of Boat (Total Length):
6) Weight of Gear (not engine):
7) Weight of People (Avg/Estimated):
8) Current Max RPM at WOT (If Available):
9) Current Max Speed at WOT (If Available):
10) Type of Drive (e.g. Alpha 1, Bravo III, etc):
11) Gear Ratio of Outdrive:

Mercury Prop Calculator:
http://www.mercurymarine.com/propellers/prop-selector/


Go through the Prop Calculator. This app has gotten very good lately. I've used a few iterations of it over the past few years and this one is pretty good.