How can I make my boat a little faster?

**Spaceman Spiff** · 02-03-2023, 02:08 PM

Originally Posted by Jim Speros;[URL="tel:3377264"

3377264[/URL]]Proper height and correct prop is most important.

That's the problem with this 1968 motor though. It takes an 11 spline prop and they are getting quite rare. I think it was actually running at 5000 though. So there's still some room there.

**Jim Speros** · 02-03-2023, 07:22 PM

Two things happen when you raise the engine with cavitation plate above the bottom. One you can introduce air to water inlets. That's why a water pressure gauge is necessary. The other thing is the prop ventilates. A standard aluminum does not like to ventilate. However, there are propellers designed to work at higher mounting heights. I am not familiar with mid size engines but there are numerous variations available for the bigger engines.
Maybe someone else can direct you towards the correct propeller.

**FMP** · 02-03-2023, 10:26 PM

Call Peter Dean at Propco Propeller in GA and ask if has a 10 1/2x15SS or whatever you think pitch, he could press an 11 spline hub into.

**FMP** · 02-03-2023, 10:35 PM

And don't lug the rpm down, let it spin happy.
What Al pitch 2 or 3 blade on it now?

**fatlenny** · 02-04-2023, 07:14 AM

Originally Posted by Spaceman Spiff

Would adding flotation foam at the transom get it out of the water a little bit more?

I didnt see anyone reply to this part of his questions, so I will add my 2 cents.

No, this will only add more weight. The reason floatation foam is added is in the case you swamp your boat. It wont sink to the bottom of the lake. Another reason foam may be added is to add support to the floor and or stiffen the hull a little.

**Dave S** · 02-04-2023, 07:35 AM

Add a 200 merc and a Vector bottom.....

........Soooo easy.......

**FMP** · 02-04-2023, 10:31 AM

Nobody answered because we were waiting to see the floating dock foam tied to the leg of motor

**FMP** · 02-04-2023, 10:47 AM

Metal flake, don't forget the flake

**fatlenny** · 02-04-2023, 11:52 AM

Originally Posted by FMP

Nobody answered because we were waiting to see the floating dock foam tied to the leg of motor

well we all know that would work, but he was asking about adding foam to the inside of the boat.

**FMP** · 02-04-2023, 01:23 PM

Starting to trend towards and old Tunnels thread

**Spaceman Spiff** · 02-04-2023, 02:50 PM

I put the Merc back on there and it the prop shaft is at about 3.5" below the bottom. The prop on it is actually 10 x 14, not 12 x 14 like I previously stated. It is 3 blade.

I now have a problem shifting the thing. With or without the shift/throttle cables attached, I'm unable to shift it out of forward. The lever will move down the track a bit, but won't come out of forward. No obstructions in the upper gear. I guess I'll have to pull the LU and see what's up. All I did was move it from the boat to the stand and back to the boat. Hoping to run out this afternoon.

**Spaceman Spiff** · 02-04-2023, 04:27 PM

Well now I'm at a loss. I pulled the LU and drained the gear fluid and it was full, and not in too bad a condition. So I refilled it and I can't turn the driveshaft by hand in either direction no matter where the dog is oriented. This thing ran and shifted great last time out.

**David - WI** · 02-04-2023, 05:02 PM

Can you turn the prop by hand?
Sometimes it's the water pump impeller sticking in the housing that makes them hard to turn.

**Jim Speros** · 02-04-2023, 06:05 PM

You should not force the shift linkage when the engine is not running. If engine is off you should spin prop shaft by hand while moving linkage.

I hope David's suggestion got you moving in the right direction.

I've got to give you credit for your ambition. When you get it together please share a pic of the lower unit in relation to bottom of boat to show water intake.