What's your cruising speed. - Page 15

psneeld · 11-14-2015, 12:39 PM

Just like in the Wizard of OZ....

"Just click your heels together three times"....

And anything is possible...

Nomad Willy · 11-14-2015, 01:49 PM

Well I clicked three times ...

But it didn't happen.

tallswede · 11-14-2015, 08:32 PM

Well, I for one appreciate the folks willing to give speed and fuel burn numbers. I gives me at least an idea what to expect from my new (to me) trawler as I learn how it performs. As one who has had planing hulls or sailboats it does me good to see how boats near mine in size/waterline perform. Personaly, I enjoy getting as much efficiency out of my cars, motorcycles and boats as I can even if they are not known to be very efficient. Getting 20+ mpg out of my 4x4 Jeep and big engine '79 TransAm is fun to me especially when I know what their performance on the other end of the spectrum is. I'm sure the same will be true for my 36' Prairie. Besides, when we take a long trip in the car or the boat, it's nice to know how far we can go on a tank of fuel. Like another has said, it can buy a nice meal at the end of the day.

Kevin

BobnDoc · 03-31-2019, 04:02 PM

Quote:

Originally Posted by Moonstruck

I cruise at 400-500 off the top. *-450 gives me 27 knots on flat, slack water.

It's really tough being in the minority again.

Hi Moonstruck

I’m almost with you. Have been running a Cutwater 30cb for two years with a Volvo D6 435hp that cruises at 18-20 knots with a WOT OF 26 knots.But those days are behind us. Recently bought a Symbol 45 (loa 48 ft., beam 15 ft) that’s powered by a pair Yanmar 440s. Had both structural and mechanical surveys done as well as a sea trial with the surveyors aboard taking measurements and running tests. At wot of 3100 rpm she did 17 knots. At what the PO called fast cruise (2800rpm) she did 14 knots. Haven’t yet checked out slower cruise results, but expect to learn that and so much more on our maiden cruise with a professional captain from Baltimore to Port Everglades in two weeks.There we’ll load her on a boat carrier vessel for the trip through the Panama Canal up the west coast to Vancouver BC. From there it’s a short cruise to the Seattle area, just in time to begin our cruising season on the Salish Sea.
Even if we eventually cruise at 8-10 knots it’s comforting to know what we have in reserve.

Pete Meisinger · 03-31-2019, 05:59 PM

My 36 Albin (single F.L. 120) does about 7 Kn, One time a tailwind pushed me up to almost 9. Always get around 3 mpg. I tell my friends that to go any faster I would need to run it over a waterfall!

Woodland Hills · 03-31-2019, 06:46 PM

We have a 63’ lwl and I cruise at 1050 rpm at 10/11 gph total which typically gives 9.7/10 kts. We can get up on plane and run at 1950rpm and 18/21 kts depending on water depth, but then we burn in the low to mid 30gph range per side. We rarely do it, but it really helps smooth out the ride when it gets choppy.

Nomad Willy · 03-31-2019, 06:52 PM

So Hills you have a planing hull then.
Are you running Detriots?

Woodland Hills · 03-31-2019, 07:12 PM

Yes, an old Hatteras with two 12v71TIs @ 650hp each. 36”x36” wheels

DavidM · 03-31-2019, 07:28 PM

Quote:

Originally Posted by BobnDoc

At wot of 3100 rpm she did 17 knots. At what the PO called fast cruise (2800rpm) she did 14 knots.

That engine is rated for 3,300 rpm and if your reported wot rpm is accurate, ie phototach calibrated, then you are 300 rpm over propped. That engine definitely doesn't like to be over propped. Many reports of valves dropped at high loads.

Calibrate your tach if necessary and check again your wot rpms. If really 3,100 then take at least 2" of pitch off of the props to speed it up.

David

geoleo · 03-31-2019, 07:30 PM

The majority on here will say 8mph 8mph 8mph I say 8mph 8mph.

MurrayM · 03-31-2019, 08:29 PM

Quote:

Originally Posted by tallswede

Well, I for one appreciate the folks willing to give speed and fuel burn numbers. I gives me at least an idea what to expect from my new (to me) trawler as I learn how it performs...

We have a Yanmar 4JH2 100hp engine (a tad too big methinks, put in by the PO) that we cruise ar 2700 rpm. This gives us between 6.5 to 7.5 knots depending on conditions, at a bit less than 1.5 gallons per hour.

The PO put in an extra 40 gallon fuel tank for a total of 140 gallons, so we have pretty good range.

cardude01 · 03-31-2019, 08:38 PM

I like to cruise at about 6.5 knots with the steady sails up.

Or 7 knots if I’m a hurry.

BobnDoc · 03-31-2019, 11:57 PM

Quote:

Originally Posted by djmarchand

That engine is rated for 3,300 rpm and if your reported wot rpm is accurate, ie phototach calibrated, then you are 300 rpm over propped. That engine definitely doesn't like to be over propped. Many reports of valves dropped at high loads.

Calibrate your tach if necessary and check again your wot rpms. If really 3,100 then take at least 2" of pitch off of the props to speed it up.

David

David
Thanks for the info. The mechanical surveyor is going to be making a few adjustments before we head south. I’ll ask him to recheck the calibrations. If they remain the same I’ll follow up with it when we get her home. If we can speed her up all the better.
Regards Bob

North Baltic sea · 04-01-2019, 01:41 AM

Hi,

6,3kn-7nm/gal is my NT-37 eco cruise speed and if douple fuel consuptions i can run ~7,8 kn, hull speed is 8,2 - 3nm/gal...

And fast cruise speed 14-15kn 1,1 nm/gal

NBs

Simi 60 · 04-01-2019, 02:05 AM

Quote:

Originally Posted by Woodland Hills

We have a 63’ lwl and I cruise at 1050 rpm at 10/11 gph total which typically gives 9.7/10 kts. .

Thanks for that .

makobuilders · 04-01-2019, 06:26 AM

Nice to see this old thread come back. Interesting info.

My panga was a planing boat but we cruised about 14 knots, inshore. When it got choppy out however my wife wouldn't be comfortable until we dropped to about 8 knots.

On my big boat 65ft, 55+ tons, I cruised 8.25 knots and never varied except to dock. Couldn't go any slower anyway since the Jimmies were at about 1300+ rpm and wouldn't want to slow them down any. I remember looking around for smaller injectors than the 55's so I could derate them a bit.

Commander Nomad · 04-01-2019, 08:24 AM

8v71n Detroits pushing 70,000lb displacement, 7.5kt @ 1100rpm yields nearly 2nm/g. 1800 rpm is 12kt and a lot more fuel.

Woodland Hills · 04-01-2019, 08:37 AM

Quote:

Originally Posted by makobuilders

Nice to see this old thread come back. Interesting info.

My panga was a planing boat but we cruised about 14 knots, inshore. When it got choppy out however my wife wouldn't be comfortable until we dropped to about 8 knots.

On my big boat 65ft, 55+ tons, I cruised 8.25 knots and never varied except to dock. Couldn't go any slower anyway since the Jimmies were at about 1300+ rpm and wouldn't want to slow them down any. I remember looking around for smaller injectors than the 55's so I could derate them a bit.

Are you saying that you idle at 1300+ rpm? My V12s idle at 650rpm and around 6.5kts, do 6-71s idle twice as fast?

makobuilders · 04-01-2019, 09:39 AM

No I was unclear. I cruised at 1300 rpm which was about 30% power, if I recall correctly. Wouldn’t want to run the engines any lower than that. Idle speed was about same as yours

Woodland Hills · 04-01-2019, 09:54 AM

We cruise at low rpm for economy, but periodically run them up for 1/2 hour or more to burn the moisture out of the oil. Folks say it’s to “burn out the carbon”, but that happens pretty quickly, it takes surprisingly long to get them fully up to temp and evaporate any condensation in the oil.