down size my prop?

[wishinIwasFishin]

g'day mate's<br /><br />got my boat going with the old merc (73 80 hp)on the week end and goes prety good with a smaller load(35 miles per hour) but really struggles to pull up a skier.<br />the boats a bell boy 16 ft f/g deep hull 1962(prety heavy) the prop that came with the motor is a 13"X 21p.<br /> What prop size would suit? should I go up to 14" and down to 19"pitch or 17" pitch<br /><br />cheers to ya all<br /><br />A bad day fishin is still better than a good day workin

 

[steelespike]

Re: down size my prop?

It depends on the rpm you are running at now.<br /> If I remember right 1 inch is good for 200 rpm<br /> (could be wrong.) I dont think you need to mess with diameter. Based on your discription I think a 2 inch drop is good just keep in mind not to over rev the motor.If you dont have a tach.<br /> you will need one. Tiny Tach might work.<br /> www.tinytach.com.

 

[Davidandkerrie69]

Re: down size my prop?

21p is rather steep hence the difficulty pulling skiers. I had a Merc 115Hp with a 15p prop and it bearly managed to pull me (>220p)out from the deep.

 

[jhreed]

Re: down size my prop?

I'm with David, I too run a 73-80hp and it uses <br />a 17 inch pitch and I'm very sure that it is in the range you need to pull a skier up with ease.. Wide open throttle should be about 5500 or slightly less... <br /><br />Jim Reed.

 

[AndrewB]

Re: down size my prop?

G'day wishinIwasfishn,<br />How is NSW theses days, hasn't totally burnt down yet, were not far behind you tho! Im like the other guys, running a 17' with a 135 merc. I dropped from a 19 and really noticed the difference, If I had my time again, I mite even drop another inch or even two just to give begginers the extra pull they need when learning or when the boat is loaded. However depending on your revs at WOT, you mite have to be weary of this, especially if they are, and probably will be, out of your recommended WOT rev range, if you can handle backing off from WOT maybe the 15 is an option. I guess it also depends how much you ski, I assume you do a fair bit of fishing too.

 

[wishinIwasFishin]

Re: down size my prop?

Thanks fella's<br /><br />It seem that from what you say that maybe the 17" is the way to go <br /> <br />and no I don't have a tacho yet as the tacho to suit is $400 oz and I can't find a dealer in oz who sells these tiny tachs and have sent tiny tach.com a couple of emails (no reply)<br /><br />and yes I mainly do fishin, it's just the kids that pester me into sking and such mainly<br /><br />cheers and thanks<br /><br />Daryl<br /><br />ps Andrew where in north west nsw and there is nothing left to burn as the drought is realy bad here (275mm or 10 1/2inchers in the last 18 month)