1973 65HP RPM question.

Yesterday was day one of season 4 for this setup.
A month ago I got the tach in finally.
4600 RPMs was the highest we got it to. (25 mph with gps unit)
This was after shifting passengers to the back.
4200 RPMs with two people up front, and two in the driver area. (22 mph)

Boat specs.
1968 Tri hull. 1200 lbs.
Rated for 110 HP and 2000 lbs total.

There were 4 people aboard 600 lbs total.
14 gallons of fuel approx 110 lbs
Everything else approx 200 lbs.

Total load was less than 1000 lbs.

We ran out about 8 of those gallons, as the objective was to get rid of the winterized fuel.

Prop is a 13 3/4 X 15 that is not perfect.

I had previously tested a 13 1/4 X 17 which I beleive was the original size.
Original's hub was bad so I did test a new 13 1/4 X 17. RPMs and speed were both lower.
Sold the prop.

I'm not looking for more speed I just don't want to hurt anything.

My questions are;

1 Will running at 4600 hurt anything? (5000 to 5500 is preferred according to the manual)
2 Any other suggestions for prop?
3 Is this just too much boat for this engine?

I'm am open to other suggestions as well.
I will try to test with just myself in the boat at some point.

Too much boat for that engine, especially if there are performance issues with the motor.

Thanks racerone. No performance issues I can tell.
The engine runs and sounds perfect. It was a 17 year sleeper, but it idles very low, almost never stalls, and gets the boat on plane rather quickly. Compression is 95 +/- 2 one all cylinders.

I just really want to know if this low RPM will hurt anything?
It is season 4 now for us so I am guessing no.
The fact that the boat is rated for 110 HP was my biggest clue it is likely too much boat.
I do have a 1976 70HP waiting for this one to die.

Thanks again for all you do for us non-professionals.

If it wasn't for people like you and Joe and JWBMarine, and others this engine never would have run, let alone see season 4. I am sure there are others like me out there.

Sorry, the boat is 17'2" long and a little over 6' wide. I had previously considered the seafoam treatment, but never tried it.
Every fuel component (and I do mean everything)was replaced when I refurbed about 5 years ago.

Also there is a 6HP 1989 on the back as a kicker as well.

Another pic.

Yes the 70 is a 1976 Evinrude.

Well I ordered the prop, but I was looking at the 73' catalog for a different reason today and I happened to see the spec.
It says 4500 to 5500 is the range full throttle operating range. I then looked at the factory manual, it said the same thing.
That is the last time I count on my memory.
Were there any updates to this?

Update! Got it out last night with the new 13P prop.
3 adults on board, so it was a similar load as before.
I lost 1 mph, (still 24 mph) but got 5600 RPMs at WOT. The whole shot was incredible.
My boss weighs about 230 lbs. and it popped him right out of the water on two skis.
He hadn't skied since he was a teenager.

Can I stick with this prop as long as we are skiing and the driver knows to keep it under 5500?
If I don't plan on skiing, take the 15P prop.
It was easy to keep it under 5500. Barely a tap back on the throttle and we were at 5300 with the skier.
It was a nice speed too!

On a side note, I had never seen the water pouring out the exhaust relief ports before. It was nice to see!
Skiing old school on wooden skies by a bunch of aging guys is a lot of fun!