check the top speed per gps today on my 19ft 260hp, how did it do? anymore left in it

Hi guys I haven't posted in awhile but I have a 1984 19ft inboard/outboard ski boat.

specs are 19ft, I/O, mercruiser MR drive, mercruiser/GM 350 rated at 260hp. The prop is a rebuilt 19 pitch prop..this is what think might be hurting me thats a great pulling prop but not too great for speed I don't think.

with me at 160lbs, 1/4 tank of gas, and nothing more than life jackets, a set of skis and other odds and ends the boat hit 51 mph per my gps which is a megellan 1440. I think on the speedo on the boat before I broke the pitot tube off I used to see it hit 55mph with just me in it..which obviously is a bit inaccurate since the gps says 51.

and my rpm looked like about 5000 rpm

My up trim button stopped working nothing more than loose wire I think but I am able to still trim up using my trailer trim which I'm not sure if it does the same angle as the regular up trim button but thats what I trimmed it up with.

it mighta had a tad more but I get scared trying to trim it up, afraid of blowing the motor.

is that good, great or not good for this boat? is there more left in it?

Re: check the top speed per gps today on my 19ft 260hp, how did it do? anymore left i

is there more left in it?

Click to expand...

Ayuh,... Go to a 21" prop to get the rpms down to/ under 4800....

Re: check the top speed per gps today on my 19ft 260hp, how did it do? anymore left i

would i get anymore speed from doing that? or would it just be easier on the engine?

Re: check the top speed per gps today on my 19ft 260hp, how did it do? anymore left i

right now you are at 14% slip. If you change to a 21 and drop the rpms to 4800 with the same slip you will get 54.2. Which is more bank for your buck or rpm in this case.

Re: check the top speed per gps today on my 19ft 260hp, how did it do? anymore left i

ok 21 pitch it is!

where is a place I can trade my 19 pitch in because from what I remember I paid a lot for this 19 pitch, like 250 bucks..I don't want to pay that again, would rather trade it in and pay a little boot maybe.

Re: check the top speed per gps today on my 19ft 260hp, how did it do? anymore left i

Hmmm... how much does your boat weigh?

I have the same engine in my 20 footer with a 17 pitch prop and it does only about 42-44 at 4600 rpm. My boat is about 4200 lbs with me and a half tank of gas in it.

Of course, that was before the drive unit blew, and I've been wondering if the drive was affecting my speed at all since something was rubbing inside it.

With a 15 pitch prop I still only got about 39mph, but that was at almost 5000 rpm, and I could go higher if I let it rev.

Erik

Re: check the top speed per gps today on my 19ft 260hp, how did it do? anymore left i

not sure on the dry weight of the boat, sorry.

I will say it's a fairly light boat compared to a searay my dad owned years ago which looks like thats what kind of boat u have.

I'd also say it runs fairly shallow because in rough big water on the lake with bigger boats making it choppy it'll knock your teeth out unless u hit waves at a angle!

Re: check the top speed per gps today on my 19ft 260hp, how did it do? anymore left i

either of you have gph numbers yet?

Re: check the top speed per gps today on my 19ft 260hp, how did it do? anymore left i

I show the gear ratio for that setup to be 1.32:1, is that orret. Beause if it is, that is not the orret prop slip.


H

Re: check the top speed per gps today on my 19ft 260hp, how did it do? anymore left i

anyone know of a good site to purchase that 21 pitch prop i want for a decent price?

Re: check the top speed per gps today on my 19ft 260hp, how did it do? anymore left i

I show the gear ratio for that setup to be 1.32:1, is that orret.

Click to expand...

Nope,... It's 1.50:1...

Re: check the top speed per gps today on my 19ft 260hp, how did it do? anymore left i

I would run the top speed test with the boat fully loaded before you go and purchase another prop, you might find loaded your rpm is right on spec and changing props a waste of money or only useful for single person driving around. 200 rpm above max rpm is no problem, I run my 90HP merc to 5800 when I am alone all the time and have had it at 6100 for short periods. Your V8 fourstroke is another animal to be sure but 200 rpm above max is not the end of the world and ensures your not lugging the motor when its fully loaded.

Save your money, the slight increase in top speed will only limit flexibility in the big picture.

Re: check the top speed per gps today on my 19ft 260hp, how did it do? anymore left i

krisnowicki said:

right now you are at 14% slip. If you change to a 21 and drop the rpms to 4800 with the same slip you will get 54.2. Which is more bank for your buck or rpm in this case.

Click to expand...

And theoretically if you changed to a 23 pitch and drop the RPMs to 4600 with the same slip you will get 58 MPH. Or you could change to a 25 pitch and drop the RPMs to 4400 with the same slip and get 59 MPH.

How much are you willing to spend to prove that the above isn't true?

weider1717 said:

with me at 160lbs, 1/4 tank of gas, and nothing more than life jackets, a set of skis and other odds and ends

Click to expand...

4JawChuck said it all in the previous post. You should be propping the boat to perform correctly with it loaded the way you normally use it. I doubt if you go skiing by yourself very often. Get another person or two in the boat with a little more fuel in the tank and your RPM will be perfect.

Re: check the top speed per gps today on my 19ft 260hp, how did it do? anymore left i

Probably not a trade item but try E-bay and Craigs List for direct sale. Buy a new prop here on iBoats.