Pilot 30 Cruising Speed- How fast are you going ?

nveater · Oct 6, 2024

So I have 1999 Pilot 30 with a Cummins 6BT 210 hp engine- this is my 3rd season with the vessel after 37 years with various sailboats. As a former sailboat guy I'm thrilled anytime I'm above 5 knots

, but it has gotten me wondering at what other Pilot owners are running their boats at. At 2400 rpm (WOT is 2650), I am cruising in the 11- 12.3 kts range ( yes I have seen higher up to 15 kts, but not very often). I do like to throttle back and cruise in the 9-10 kts range. I realize that this Cummins, a very reliable engine, is probably the smallest hp engine for the pilots and that later iterations with the Yanmar had a bunch more HP. So I would love to know if other Pilot owners with this model engine are seeing similar speeds? More curious than concerned -

Thanks

Mainship Pilot · Oct 6, 2024

2004 Pilot II 30, 6LPA 315 Yanmar, I typically cruise at 2800 rpm's, with a tow, 11' 325# console style dingy behind. I keep it there around 14 knots, as the dingy likes that speed. If not towing, I gain about a knot, at 3000 RPM's, it's a 16 knot cruise, depending on wind and sea conditions.

Mainship Pilot · Oct 6, 2024

Mainship Pilot said:
2004 Pilot II 30, 6LPA Yanmar, I typically cruise at 2800 rpm's, with a tow, 11' 325# console style dingy behind. I keep it there around 14 knots, as the dingy likes that speed. If not towing, I gain about a knot, at 3000 RPM's, it's a 16 knot cruise, depending on wind and sea conditions.

nveater · Oct 7, 2024

Thanks very interesting that extra 100 hp from Cummins to Yanmar, very nice

DavidM · Oct 7, 2024

Well, that same Cummins block can be had with 380 or even 425 hp.

The Yanmar 6LP at 315 hp is a perfect match for that boat.

But enjoy your Cummins 210 hp engine. You could run it at wot and it probably wouldn’t hurt it at all. That is according to Tony Athens, the Cummins guru on Sbmar.com.

210 hp should push it to similar speeds as the Yanmar at 2,800 rpm.

David

Mainship Pilot · Oct 7, 2024

DavidM said:
Well, that same Cummins block can be had with 380 or even 425 hp.

The Yanmar 6LP at 315 hp is a perfect match for that boat.

But enjoy your Cummins 210 hp engine. You could run it at wot and it probably wouldn’t hurt it at all. That is according to Tony Athens, the Cummins guru on Sbmar.com.

210 hp should push it to similar speeds as the Yanmar at 2,800 rpm.

David

David, Assuming your last statement, the 6LPA burns about 7.5 - 8 GPH at 2800rpm in my Pilot 30. What would you guess the Cummins 210 would burn at that same RPM, assuming that's WOT or thereabouts?

DavidM · Oct 8, 2024

Well, your 6LP makes about 18 hp per gpm of diesel so it is producing about 8*18= 144 hp, much less than the Cummins at wot- 210.

If they were both making the same hp, the fuel burn would be about the same.

Remember, the Cummins makes its maximum hp at about 2,600 rpm, your 6LP makes it at 3,800 rpm.

David

nveater · Oct 8, 2024

So for fuel burn- I ran my Cummins pretty much in the 2400 range the first two years I had it and I was getting about 6.8 GPH- this year I have been running it for longer periods at lower rpm (2K or below) and have averaged 3.7 GPH- one of the drawbacks of the higher rpm is the noise. The engine bay is insulated but I was going to ask this forum about what they have down for sound proofing. At 2400 as I said I get between 11.5 and 12.3 kts- I have pushed it to 2600 and am getting 15+ kts there but am sort of nervous about running it at WOT for very long- this is (for me) an interesting discussion and I appreciate all the comments and insights- I am also wondering whether I am propped correctly- (I do have my prop information but its on the boat)

Mainship Pilot · Oct 8, 2024

Noise is probably the biggest drawback of the 6LPA, it’s LOUD at cruise! When we cross to Catalina, 26 miles, it’s pretty much in silence between the admiral and I. Otherwise we would just be yelling!

Duetto · Oct 9, 2024

fwiw, we have run our yanmar 4jh3's at 3400 (3800 wot) for 20 years/4000 hrs. this is not on our mainship but a commentary on how you can run a diesel.

BB-marine · Oct 13, 2024

nveater said:
So for fuel burn- I ran my Cummins pretty much in the 2400 range the first two years I had it and I was getting about 6.8 GPH- this year I have been running it for longer periods at lower rpm (2K or below) and have averaged 3.7 GPH- one of the drawbacks of the higher rpm is the noise. The engine bay is insulated but I was going to ask this forum about what they have down for sound proofing. At 2400 as I said I get between 11.5 and 12.3 kts- I have pushed it to 2600 and am getting 15+ kts there but am sort of nervous about running it at WOT for very long- this is (for me) an interesting discussion and I appreciate all the comments and insights- I am also wondering whether I am propped correctly- (I do have my prop information but its on the boat)

The max fuel burn for a 210hp 5.9 cummins is 11.2 GPH This would be 100% load. Using 210hp/11.2 gpg = 18.75 hp per gallon burn. 100% load= 11.2 GPH, 80% load = 8.96 GPH. This would be the goal I would shoot for 80% load would be an efficient and maintain the longevity of the 5.9 L cummins @210. 80% load would be using about 170 hp.

Based on your fuel burn 6.8 gph and 2400 rpm I believe you either have wrong fuel burn calculations or or you are under propped. Based on your max rpm posted on this forum 2650 rpm you would be correctly propped or slightly over propped. The rule of thumb is 100 to 150 rpm above rated HP RPM which is 220@ 2600 rpm.

My guess would be your fuel burn numbers are a bit off. Using 12Kts = 13.8mph as an average speed at 2400 rpm @ 6.8 GPH would give you fuel economy of 2.03 mpg. 2400 rpm @ 8.96 gph ( my calculation)= 1.54 mpg which I believe is a true realistic number for continuous run at 2400 rpm. I do believe that if you cruise at 2400 rpm for a trip you may see that your overall fuel burn may be 6.8 gph if you add the engine hours of the trip to fuel burn amount. Example: Start engine hour meter running, untie, leave harbor, allow engine to get up to temp, start to advance throttle, set cruise at 2400 rpm, slow for a few no wake areas..... you get the drift! Your overall fuel burn may be 6.8 gph. The best way to get true fuel burn for speed. Distance traveled divided by Engine hours ( start engine shut engine off) = average speed. Fuel used divided by average speed = mpg for that average mph Now you know mpg for a specific speed. Advance the boat to that speed and compare Speed to RPM.

Example: @ 9mph the fuel economy is 2.5mpg. Throttle the boat to 9 mph. what rpm is the engine running 1800 rpm ( hypothetical #) = 1800 rpm =2.5mpg , 9 miles in one hour divided by 2.5 mpg = 3.6 gph @ 1800 rpm this is not referring to fuel burn of the 210 cummins. Just an example.

This is a lot of information that most could careless, I know! But it is a good way to know accurate average fuel burn and know that your engine is maintaining it. You have a base line. When it comes to decided you have the right prop. The engine manufactures did that homework for you. The engine manufactures give you a max rpm for rated HP. The manufacture says the engine/boat is propped correctly if the engine can turn the max rpm preferably +150 rpm @ WOT. 210 Cummins anything above 2600 rpm when operated with full load and fuel. The boat and engine are propped correctly.

nveater · Oct 15, 2024

Thanks BB, I appreciate your taking the time to write all this out- I am about to be hauled for the year- so Ill bring all my logs home and go over my calculations- so under way I can just get to 2600 (2590) on the analog tach (can't vouch for its accuracy) so I may be somewhat under propped. This a bunch to ponder and plan for over the winter - Thanks again

adornato · Oct 21, 2024

This is not what you asked..but,, cant resist. My 2002 Pilot 30 with yanmar 4LHA-stp turbo runs 16 kts all day long at 2850 rpm. WOT is 3250 rpm.
Consistently burns about 5-6 gal per hour..
I wish I had 315 hp but then again I wouldnt want to try to slither down there to service it and the noise level would be worse.
oh and I did I tell you the boat is for sale right now in San Rafael CA?

adornato · Oct 21, 2024

BB-marine said:
The max fuel burn for a 210hp 5.9 cummins is 11.2 GPH This would be 100% load. Using 210hp/11.2 gpg = 18.75 hp per gallon burn. 100% load= 11.2 GPH, 80% load = 8.96 GPH. This would be the goal I would shoot for 80% load would be an efficient and maintain the longevity of the 5.9 L cummins @210. 80% load would be using about 170 hp.

Based on your fuel burn 6.8 gph and 2400 rpm I believe you either have wrong fuel burn calculations or or you are under propped. Based on your max rpm posted on this forum 2650 rpm you would be correctly propped or slightly over propped. The rule of thumb is 100 to 150 rpm above rated HP RPM which is 220@ 2600 rpm.

My guess would be your fuel burn numbers are a bit off. Using 12Kts = 13.8mph as an average speed at 2400 rpm @ 6.8 GPH would give you fuel economy of 2.03 mpg. 2400 rpm @ 8.96 gph ( my calculation)= 1.54 mpg which I believe is a true realistic number for continuous run at 2400 rpm. I do believe that if you cruise at 2400 rpm for a trip you may see that your overall fuel burn may be 6.8 gph if you add the engine hours of the trip to fuel burn amount. Example: Start engine hour meter running, untie, leave harbor, allow engine to get up to temp, start to advance throttle, set cruise at 2400 rpm, slow for a few no wake areas..... you get the drift! Your overall fuel burn may be 6.8 gph. The best way to get true fuel burn for speed. Distance traveled divided by Engine hours ( start engine shut engine off) = average speed. Fuel used divided by average speed = mpg for that average mph Now you know mpg for a specific speed. Advance the boat to that speed and compare Speed to RPM.

Example: @ 9mph the fuel economy is 2.5mpg. Throttle the boat to 9 mph. what rpm is the engine running 1800 rpm ( hypothetical #) = 1800 rpm =2.5mpg , 9 miles in one hour divided by 2.5 mpg = 3.6 gph @ 1800 rpm this is not referring to fuel burn of the 210 cummins. Just an example.

This is a lot of information that most could careless, I know! But it is a good way to know accurate average fuel burn and know that your engine is maintaining it. You have a base line. When it comes to decided you have the right prop. The engine manufactures did that homework for you. The engine manufactures give you a max rpm for rated HP. The manufacture says the engine/boat is propped correctly if the engine can turn the max rpm preferably +150 rpm @ WOT. 210 Cummins anything above 2600 rpm when operated with full load and fuel. The boat and engine are propped correctly.

When doing these calculations about fuel burn on my recreational boat which I drive less than 100 hours a year, I recall my son questioning this process, asking me what percentage of my total income am I wasting on recreational marine diesel fuel. The answer is always the same: "not enough"..

Mainship Pilot · Oct 21, 2024

adornato said:
When doing these calculations about fuel burn on my recreational boat which I drive less than 100 hours a year, I recall my son questioning this process, asking me what percentage of my total income am I wasting on recreational marine diesel fuel. The answer is always the same: "not enough"..

Exactly! Fuel is always the lowest cost of boat ownership, unless you are a commercial operator.

rgano · Oct 21, 2024

OP also asked about noise reduction measures. There is darned little one can do to reduce the noise from the side exhausted 6LPA at full throat. However, there are things one can do to reduce some of the other engine noise at the helm coming via other routes. I have it from the wife of a fellow 30 Pilot II owner here in town that my hardtop model is a good deal quieter than their 30 Pilot II hardtop. I have covered the underside of the engine hatch with Sounddown, applied egg crate sound absorbing material under in the engine compartment air intakes under the cockpit gunwales and to the inboard sides of the fuel tanks. Rubber cowl sealing strips have been added atop the coaming around the engine and cockpti hatches, and sound absorbing hard tiles from SoundDown have been epoxied to the prop tunnel. When on long trips we don our shooting earmuffs with Sena motorcycle intercomm units added to them. What'd you say???

nveater · Oct 21, 2024

adornato said:
This is not what you asked..but,, cant resist. My 2002 Pilot 30 with yanmar 4LHA-stp turbo runs 16 kts all day long at 2850 rpm. WOT is 3250 rpm. Consistently burns about 5-6 gal per hour.. I wish I had 315 hp but then again I wouldnt want to try to slither down there to service it and the noise level would be worse. oh and I did I tell you the boat is for sale right now in San Rafael CA?

Hindsight being 20/20, I would today look for a pilot with one of the Yanmars or a bigger Cummins, but for the type of cruising I do the 12-13 kts is certainly sufficient- another post in this thread talked about my boat being potentially under propped- I have a 4 bladed LH prop of 21X25- it looks like this prop was purchased by the PO- I am not sure I want to spend $$ to buy a new lower pitched prop, but....

rgano · Oct 21, 2024

nveater said:
Hindsight being 20/20, I would today look for a pilot with one of the Yanmars or a bigger Cummins, but for the type of cruising I do the 12-13 kts is certainly sufficient- another post in this thread talked about my boat being potentially under propped- I have a 4 bladed LH prop of 21X25- it looks like this prop was purchased by the PO- I am not sure I want to spend $$ to buy a new lower pitched prop, but....

At 22X24X5 with my 6LPA-STP Yanmar 315, I was over-propped unable to achieve more than 3600 RPM and sooting up the side of the boat where the exhaust is. Dropped two inches of pitch at the prop shop and all is well.

As to cruising at less than "over-the-hump speeds, which occurs on my boat at 13-14 MPH at 2700-2800 RPM, RPM below that range sees me nose up and unable to see where I am going very well until I throttle back to closer to hull speed of 7-8 MPH. That's why you'll never see me putting along for any length of time below planing speed carboning up the turbo,

Mainship Pilot · Oct 21, 2024

rgano said:
At 22X24X5 with my 6LPA-STP Yanmar 315, I was over-propped unable to achieve more than 3600 RPM and sooting up the side of the boat where the exhaust is. Dropped two inches of pitch at the prop shop and all is well.

As to cruising at less than "over-the-hump speeds, which occurs on my boat at 13-14 MPH at 2700-2800 RPM, RPM below that range sees me nose up and unable to see where I am going very well until I throttle back to closer to hull speed of 7-8 MPH. That's why you'll never see me putting along for any length of time below planing speed carboning up the turbo,

You east coast guys always use MPH, vs knots, then I have to do math in my head!

At 2800 rpms, I cruise at 14-14.5 knots in slack seas and tides, when towing, it’s closer to 14 knots, or a bit slower, but the bow stays at the same level. My tow likes it right around 14 knots in average seas.

rgano · Oct 21, 2024

ALL of the ICW and western rivers are marked in statute. It became pointless not to shift from knots.

rslifkin · Oct 22, 2024

rgano said:
ALL of the ICW and western rivers are marked in statute. It became pointless not to shift from knots.

I run into that issue in the Great Lakes, NY Canals, etc. But I always end up just converting everything into knots and nautical miles for my own use, as that's what I'm used to for boats (and many of the sailors do the same, it's only the powerboaters around here that use mph).

BB-marine · Oct 26, 2024

adornato said:
When doing these calculations about fuel burn on my recreational boat which I drive less than 100 hours a year, I recall my son questioning this process, asking me what percentage of my total income am I wasting on recreational marine diesel fuel. The answer is always the same: "not enough"..

I agree with you. At 100 hours a year which is the average boaters usage who cares? For me I have other reasons why I did the calculations. (1) I purchased the little 34' Pilot for cruising. We purchased it in 2021 and I have put 900 hours on the engines with over 7000 miles under the keel. Finding the "sweet spot" for fuel economy was important when fuel was at average of $5 a gallon 2022 and 2023. 2022 to 2024 I have burned 3600 gallons of fuel spending a lot of time on the water. That gives an average burn of about 4 gph. There is a lot of idling and a lot of 2600 to 2800 rpm running in those hours. Another reason to do calculations is to make sure the engine was loaded properly based on the manufactures torque curves and fuel usage curves. The Mainship pilots have a semi displacement bottom with a tunnel. The twin engine version does not have a lot of room for blade tip clearance. Finding the best prop for performance, noise, and load can be a challenge. I had the props tuned based on rpm and fuel burn. I worked with a prop shop and they tuned both 18" X 25" four blade props to be 17" X 25.5" with a .060 cup to be the prop to work for the way I had the boat loaded. My rpm was a bit over propped at 3400 rpm WOT but my performance was overall good. You are correct most don't need to do the calculations. I even stated that in my post " a lot of information that most could careless" For me, when the boat is in the water I like the prop to be turning! That's more than 100 hours a year. Enjoy burning that fuel !

Pilot 30 Cruising Speed- How fast are you going ?

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