Newbie needs prop advice

[MTWaterdog]

Howdy all!
I recently bought an 1984 bayliner aq131a 275. After countless hours of rehab I got this thing running great! Books and internet are wonderful tools.
Unfortunatly there is one thing that I am having a diffucult time finding. That is which prop to use for my boat.
I was driving down a dirt road with the boat in tow (most roads here are dirt/gravel) and I threw a rock that took a chunk of the prop out. Note to self, cover prop with canvas or other heavy protective cover.
I primarily use it for play, tubing, skiing etc...occasionally fishing.
I seem to find various props that will work, but I want one specific to my use and sterndrive.
I cant get any numbers off the old prop...
Any ideas? All your help and ideas are greatly appreciated.

Also I was reading that when you go to a new prop that you need to buy an exchangable hub kit. Is this correct?
thanks again

 

[MTWaterdog]

Re: Newbie needs prop advice

I did find the following stamped on the inside of the prop. Michigan smc 344. I cant seem to relate it to anything.

 

[MTWaterdog]

Re: Newbie needs prop advice

So I managed to find what I am looking for after 2 head splitting hours on message boards and google. I found a prop guide at volvo penta that lists my motor/drive combination.

Standard hub, LH. There are a few choices depending on how hard I want to push my motor.

Of course faster is better, but i have read that too much prop can be too hard on the boat.

19' typical load. skiing, tubing..
3600-4000 rpm WOT.
I have a choice of 14x17, 14x19, 15x15, and 15x17.
I am leaning toward the 15x17 as it seems to be in the upper middle range of speed.
Any thoughts?

 

[reelfishin]

Re: Newbie needs prop advice

I'd try and find out what the old prop was before just guessing. Most boats can't handle a very big change in prop pitch or diameter. Going to a higher pitch will take away from your hole shot and often can even drop top end speed as well.
I'd be inclined to lean toward the 15" 15P prop if your pulling a skier but I tend to prefer a larger diameter prop and lower pitch for better 'bite' on a heavy boat.
You may need even a lower pitch to be really happy with it's performance. A higher pitch rarely equates to more speed, especially if you making a big jump.
You need a starting point to go with then fine tune your choice from there by knowing the plus' and minus' of a particular set up.

 

[steelespike]

Re: Newbie needs prop advice

A prop shop can fix your prop and tell you the pitch. Then run the boat
get the max rpm and speed ,hole shot? look on motor for rpm range specs.
If a prop change is needed keep the old one for a spare.
Don't change props without the info and a good working tach.

 

[72SideWinderSS]

Re: Newbie needs prop advice

You might try this:
http://forums.iboats.com/showthread.php?t=257604

 

[mickjetblue]

Re: Newbie needs prop advice

I settled with the 15 x 17, although I use my boat mainly for cruising, with
some occasional skiing or boarding.

The 14 x 19 also works fine, although the 15 x 17 has a higher top speed.

Trade-off exists in all prop differences, and I think your engine condition and
boat, including boat load and pulling load, all factor into what is best.

If skiing was the main activity, I'd probably go with the 14 x 19.
You have a nice combo, take good care of it.
Good luck, and enjoy your boating!

 

[Robj]

Re: Newbie needs prop advice

I have a 15 X 17 on mine and have the same engine as you. Will really test it out this weekend, but just for cruising, can't really open it up without over revving. But that is OK, because will use it for skiing so it is a trade off. Need that hole shot and willing to give up a little speed to get it.

Your WOT should be closer to 5k rpm, not 4k as you stated earlier. I believe what you stated was for the GM motors, and yours is not, it is a Volvo.

Have a great day,

Rob.