Cruising at 5-7 Knots in a Power Boat

[foggysail]

I made the transition from sail to power (40' Silverton aftcabin) 6-7 years ago. Needless to say, paying for fuel was a nasty experience, one we accepted for the convenience power provided. But we thought we were flying in the sailboat at 6K so going slow is enjoyable; half the fun is getting there!

OK, with that stated I checked with Borg-Warner for problems free wheeling their Velvet transmission at slow speeds. I was told by them there is no problem free wheeling the transmissions in the 7-8K range.

Since then, I operate only ONE of my 454s at a time except when docking or when absolutely necessary. And that operating engine runs about 1500 or so RPMs for about 7K SOW. Fuel consumption is around 1.4-1.6 M/gallon or about 10G/hour.

Tanks hold 300 gallons and most years 1 complete fill gets me through the season.

Foggy

[larrylwill]

thanks for that information, I'm thinking on trips to Florida and at 10gph Its 385 miles by road at 7 mph that would take approx 55 hours not including locks so thats 550 gals or about $2750 a little much. In contrast 1/2 gal per hour = $137.5 ($5 gas).
So thats my goal. I really like the layout of a lot of cruiser I have seen and like sailboats that are pretty cheap now. I think I could get a pretty decent cruiser for under $10k and if one could be fitted with a small 30hp diesel for under $10k I believe would make a decent boat, although I have no Idea how efficient a cruiser is at 5-7 knots compared to a sailboat or trawler.

[zeta]

How about something like this: 1982 CAPITAL YACHTS Gulf 29 Sail Boat For Sale - www.yachtworld.com

[larrylwill]

I like it $1500 to ship not bad. Might be a good place to look. What did you search for? I never found that with any of my searches or saw any that looked like it.

[zeta]

I just remember seeing a few of these for sell for less than 20k and thought they would make a nice cruising boat with the option to sail.

[larrylwill]

I searched for sail boats, cruising boats yachts etc and never came up with it. The only minus I see is the draft at 4ft but not that bad. The willard trawler I was looking at had a draft of 3.5ft and was 32ft but would cost $2500 to ship and needed work, delaminated teak etc. About the same price got 1/2 gph also.

[DeepSeaDan]

I just picked up a 1981 Chris Craft 281; 29' powered by twin 305s (gas). Inside of 100 miles I had 9 to choose from under $20K.

I'm still trying to work out the consumption numbers myself. If I had to guess now, 5-7 knots would give me about 10 gph rate with the boat planed and both engines at 2000 rpm.

[larrylwill]

10gph is a long way from .5gph

[markpierce]

At those speeds you should be looking for a diesel-powered boat with no more than 80 horsepower. My 14-ton boat with a naturally-aspirated John Deere 4045D reaches hull speed of 7.8 knots at full power. At five to seven knots, I'd be using between 25 and 65 percent power, without the assistance of sails. We're talking about 1 and 2.5 gallons per hour.

[Cheechako]

Originally Posted by Waterwayguy

We have a Marine Trader 34 DC. Click on our Beach House site on my signature line. Chuck

There was a trader 34 dc up here for sale with lehman diesel for $15k this summer... so keep looking! I see no problem doing what you are suggesting (250 hp at low speed) you should open it up now an then. there's a bayliner model built in the 70's 80's that is like that; not really a planing boat or at least powered such that it wont very well. noted for decent fuel usage. Not a hot seller though! There was a nice one up here for about $8k with trailer. If you have a good working gas engine, not sure putting the diesel in would break even...

[Vyndance]

Originally Posted by DeepSeaDan

I just picked up a 1981 Chris Craft 281; 29' powered by twin 305s (gas). Inside of 100 miles I had 9 to choose from under $20K.

I'm still trying to work out the consumption numbers myself. If I had to guess now, 5-7 knots would give me about 10 gph rate with the boat planed and both engines at 2000 rpm.

5 to 7 knots will be just off idle and no where near planing.

[Florida Mike]

Is trawlers are hard to find and you are handy you might consider a sailboat take the mast and ringing off then cut the keel off. This should give you a boat for your speed and fuel consumption. Just my two cents, Mike.

[River Cruiser]

A guy stopped in the marina this afternoon in a converted sailboat. It is 24' LaPaz, no mast 18" draft and a 13 hp Kubota 2 cylinder diesel that averages 1 quart per hour at hull speed. He has added a hardtop with windows that tilt out, it is a rather unique looking boat.

[clockwork orange]

I think the La Paz is a pilothouse motorsailor so it sounds like the guy just removed the rig, that is some very economical cruising.
Steve,

[Cheechako]

There's a difference between a 32 ft trawler and a 32 ft sailboat though. Huge amount more room, light and accomodation in a trawler. Most trawlers have wide, somewhat flat hull aft compared with a sailboat. A sailboat without a mainsail is gonna roll real bad in some circumstances. (the reason we often motor in choppy seas with at least the main up) But sure it can be done. If your gonna motor the sailbaot... at least keep the mainsail!