Speed

[Serenity]

While coming back from Fire Island Inlet, the bay was calm and no wind, it was flat. I put the pedal to the metal and the Yanmar 315 hit 3793 rpm's and 29.8 knts on the GPS. Temp (160) and oil pressure had no movement. Fuel tank was 3/4 full. I was maintaining my speed next to a buddy of mine who was running his 13' Whaler with a 50 HP Yamaha. What a great boat. No fish though.

[Mark Deeser]

Life can be good, sometimes we get to sit back an just enjoy the ride. Life as it should be.

[jcollins]

That is great! Over 34 mph. My boat has never seen speeds like that.

[Serenity]

John, I think one of the reasons for the speed was I had the bottom media blasted, sanded, three coats of barrier and two coats of abative. There was 10-13 years of bottom paint on the hull.

[Tree]

That is great! Over 34 mph. My boat has never seen speeds like that.

Nor mine - even with the tide!

[N4QC]

Another contributing factor to the excellence performance of 29.8 knots would be the fuel temperature. Suspect that the fuel temperature was in the order of 25C/77F. Max rated output for the Yanmar 315 is 3800 rpm at a fuel input temperature of 25C.

Nice numbers…

Have fun,

[Serenity]

Works for me.

[John_Madison CT]

That I would need to see to believe. That's one fast 28TE.

[RobS]

That I would need to see to believe. That's one fast 28TE.

Max is running the original gear box from the Penn engine but he's been repowered with a faster spinning Yanmar. I have been aboard - she hits those numbers.

[Serenity]

Rob, thanks for the back up. If I can find a decent day I will post a video of the numbers.

[Cape Codder]

Twice a year our 28 with a Yanmar 6LP hits speeds comparable or even greater. Every time it's hauled to and from the harbor.
26 knots is top end for Santosha when in the water. Perhaps we have the wrong tranny.

[Tree]

Max or Rob, do you know what the gear ratio is on the Pennisular transmission?

I've always felt that the 300 yanmar seemed on the edge of underpowered for a boat that can really turn some speed but clearly it isn't.

Its got me thinking about propeller choices now - for example my buddy is running a 2005 28 now, with a 20 x 18 x 5 cup prop but he doesn't have the trolling valve gearbox (not sure if the ratio is the same). He can cruise at 18 knots all day long around 3100 rpm where as i would be about 3400 rpm and his WOT is the same rpm at 3850 yet he gains almost three knots over me.

We are running a 19 x 19 5 cup prop that he had on that boat due to ours loosing too much area when we needed to have it reworked after our electrolysis issues last winter. When he had this propellor on that boat - the speed was only marginally different to what he has now.

If you can tell me the ratio of the gearbox it will all help with the data towards developing the correct propeller for or boat.

18 knots seems to be the sweet spot for these boats and it would be nice to have that at lower revs without compromising WOT.

Obviously I am not expecting to see the figures you have achieved - just an improvement on the cruising speed if possible

[RobS]

She's a 1.56 ratio. You should look into the new DQX prop, I have heard very good things.

[Cape Codder]

I'm running 18knots at 3100 also.
I'm running to Martha's Vineyard Saturday. See if I can grab a picture of instruments.

[Tree]

She's a 1.56 ratio. You should look into the new DQX prop, I have heard very good things.

Thats quite a bit different to the Hurth then - I think its something like a 2.1 ratio and 2.4 for trolling? With regards to the Propellor, its probably something not practical to get my hands on over here but I will look into it with regards as to what can be designed over this side.

Bob have you got the trolling valve style gearbox?