Prop question/suggestion/problem

Because I have whined about it so much the boat was so far back haha.
Its a 1994 American skier Tbx 350 merc 1:1

Wonder If I should call up eric at oj and see what he says.

Ok I'll jump in with the "fuzzy" guys here.

What I'm fuzzy about is why you don't figure out what the boat had for performance when it was new and down in the flatlands then you can figure out what it realistically is capable of at altitude

How are you gonna do that you ask?

Pick up the phone and call the guy who has been more than a little familiar with American Skiers over the years. At different times he has worked there designing the boats or later on owned the company. You go to his website so you should be familiar with him since he's on it frequently.

I'm sure he could tell you what it would do speed wise at sea level, what it has for an engine, what it's power was, whether that hull has lots of drag etc

You're up 5000 ft so your power is down by about 15% to start with no matter what.

Here's his number 985-542-4336, just ask for Ron You'll get a lot of good info on the phone actually talking to him.

Good luck
KenO

Hollywood wrote: KENO wrote: You're up 5000 ft so your power is down by about 15% to start with no matter what. not according to someone on here who i won't name but it starts with T and ends with j.

Per the Wallace Racing engine HP/altitude calculator, it looks like 10% is a closer figure at 5000'

Engine has how many hours on it?

@ 5000' it's spitting out 15% exactly

Hollywood wrote: @ 5000' it's spitting out 15% exactly

Pete's abacus obviously had a malfunction

Can you demo that 11" OJ?

Woof, TBX is a big girl. 2650lb

Orlando76 wrote: I think it'd be easier to move to sea level.

So the rock solid ski boat advice we're giving you is to move to the coast and lose 30 lbs. Problem solved!

In my simple mind after reading a lot of stuff about speed vs. HP, I've come to believe that in small boats in the 17-23 ft. range it generally takes 11-13 HP to gain 1 mph. Inboard ski boats, with the shaft angle and design purpose of planting the bow, may take a bit more, 13-15 HP to gain 1 mph. If we take the 15% power drop that is mentioned above as being 260 HP x 15% = 39 HP, then we're I think pretty much agreeing your engine is putting out more like 220 HP, and at 900 hours maybe it's even 210 HP. My point is that I'd expect about a 3 mph drop from running that same boat at sea level.

Thanks for that I did not know the specific numbers. I think ill try the new oj prop and then just be happy and save up for a gt40 176 if I can find one in a few years.

Hollywood wrote: KENO wrote: You're up 5000 ft so your power is down by about 15% to start with no matter what. not according to someone on here who i won't name but it starts with T and ends with j.

It's not really debatable. It's physics. Your BHP loss computed from your BHP of 260 at sea level and Elevation of 5280 feet is 41.18 HP loss.

Make sure that thing is tuned up right. That OJ prop has less blade area, another helper in getting more RPM. The American Skier Advance hull doesn't seem to react significantly to aft weight for speed gain, but do play around with this some. Run minimal weight inside the boat especially up front (passengers). Running a full tank of gas may actually help as you said the rearward weight did pick up some speed. That hull does plow quite well, you may *want* to maintain some aft weight.

Get an extended pylon and shorten up your rope to 70'.

Your engine will be happiest running higher RPM but you may find that the pitch sacrifice (& other prop design features) will not produce highest top speed. The ACME rake is also going to help get the nose up, more speed to be gained.

We really need to find out how many RPMs you can really pull, then narrow down the prop selection. Really.

Shorter rope = less rope = less weight. You are holding the rope, you're supporting its weight.
Shorter rope = more upwards angle = less weight supported by your feet (skier + rope)

Consider ditching the tower.

Hollywood wrote: Run minimal weight inside the boat especially up front

SharkSN stripped down a green TSC "superwake" and replaced a bunch of [necessary] components with carbon fiber.

Fluid Motion Sports

I have found a OJ 304 13x11 .9cup forsale used and im going to buy it hopefully today. I hope it works out well. If the CNC OJs are close to the acmes It should be right inbetween the 913 and the 1609

Keno, I really appreciate the offer. I just bought a prop today Its a XMP OJ 13x11. And I also looked the other day and my buddies spare prop is a old13x12 so I threw that on my boat last night just to try. It would probably give about the same results as yours. I really appreciate the offer tho.

Im going to test this weekend. I just put it on last night.