28 TE 315 Yanmar, fuel burn, speed, prop etc

[RichN]

I am the new owner of a 2008, 28 TE flush deck and I have a few question, which I hope the community can answer.

Boat Info
- 315 Yanmar 6LPA-STP2
- ZF/Hurth 2.00:1 gear
- Hard Top

- What is ideal cruising RPM
- What is speed at this RPM
- What is fuel burn at this RPM, assuming 4 people 3/4 fuel
- What prop size are others running on a similar set up
- What is you max RPM with prop noted

Any assistance is appreciated

Rich N

[PCStudios]

Hi Rich,

I am getting ready to do a fuel fill. Let me get some numbers, and I will get back to you. This is only the second tank since we purchased the boat last November. The first tank had a lot of slow running and idle while working was being performed. But now we are running weekly so will start to dial in fuel burn.

[Tree]

Fuel figures are between 2.2 and 2.5mpg imperial. Cruise for me is around 18-19 knots at 3300 rpm but then I’ve played around with propellers I’ve had developed. Before with the standard wheel was around 17 knots. WOT before was 22 knots and now just shy of 26. These numbers are usually on a loaded boat with two large people.

[RichN]

What size props are you running with 315, 3 blade???

[Tree]

4 blade 20.5 x 20.5 made by Clements marine

[PCStudios]

My recent numbers:

Engine box boat
Yanmar 6LP-STE, 1670 hrs
Prop 19 x 19, 5 cup, 4-blade
Ratio is 2.03

Last 93 gallons, mostly running 34-3500, 15.5 to 16.5 kts was 6.4 gal per hour.
This was full cruising load with two people,
WOT says 3800-3850 on Yanmar tac. Need to check those numbers.
WOT 20.5 kts

Bottom will get stripped this winter, and a stand off old through hull removed.

I like TREE’ numbers. Going up 1.5” in pitch and diameter.

[PCStudios]

Tree,
What did the prop cost? Are you willing to give the detail specifications?