Speed and mileage

[booboo2]

Hey folks,

I am a long time lurker, just joined awhile back.

I am looking to buy a boat in the not to distant future. I am leaning towards a 35 to 40 ft monohull sail boat or possibly something like a 35 to 40 ft. Carver or similar . I am trying to find out what the speed while motoring on average is, as well as how many miles to the gallon. I realize these figure may vary greatly. If you could just say what type and size boat you have, the type of engine with the mileage that would great thanks. I tried searching to no avail. I have zero sailing experience, that will change soon. I also posted this in the sailboat area, if you answered in that thread many thanks.

Boo Boo

[eyschulman]

Your question is so very broad it covers the full spectrum of speed and fuel burn power and sail. It would be much better if you can get to a point where you have a better idea of what type and size boat with particulars as to hull and power. You may not have to ask the question if you do some basic reading about hull types and fuel burn. This will also help you choose what type and size boat you need.

[pistarckle]

The sailboat is easy , around 6 kts and less than a gallon an hour .
The 35 foot Carver with two gas engines , motoring on a plane , 20 to 30 gallons per hour .

[Stu Jackson]

Welcome.

Please be advised that while motorboats may measure speed in miles per gallon, like automobiles, most sailors simply measure gallons per hour in fuel consumption, then extrapolate that based on speed to determine range on a tank of fuel.

Our boat, by keeping careful fuel refill logs, has used 0.493 gallons per hour for the past 15 years. My fuel gauge doesn't work and I won't fix it until i sell the boat, maybe the day before. I could care less about the gauge, which is useless with a non rectangular tank anyway.

23 gallon tank, 20 useful, 1/2 gallon per hour, at five knots.

I could do the math...

KISS.

[GPSocal]

booboo2
A 35' powerboat is going to burn lots of fuel, diesel or gas, depending on how fast you travel. A sailboat certainly much less fuel burn but some of that saving will be offset by sail replacement costs.
While you are deciding between sail and power, try out a charter for a few days or longer to get a feel for the characteristics of each. Great advice on this forum but you will find partisan responses depending the type of boat owned.

[hellosailor]

Speed of sailboat, maybe 6-7 knots.
Speed of powerboat, is only limited by your wallet. 15-20 knots, or 60 knots if you can afford it.

If the thought of dropping $500-1000 at the fuel pump on a daily basis bothers you, think along the lines of a 20' power boat instead.

Sailing is not a fast way to get much of anywhere.

[eyschulman]

Just like to get something straight. A boat with a mast and sailing rig with a motor driving it is a power boat by both law and reality. Many sailors who put down power boats for their supposed fuel burn are overdoing it. Cut a sail boats mast off and you have a very fuel efficient power boat. As a matter of fact before the development of the modern mega HP motors almost all power boats were highly fuel efficient. For those who want truly fuel miser motor boats they are available and some of them can exceed 6 knots. When it comes to fuel burn one has to get into stuff like waterline length-beam-displacement and wetted surface. Actually most sail boats under power are probably not as economical as one might think due to all the ballast weight they carry. A boat of similar dimensions and much less weight without the lead and less windage would probably be more economical under power as a pure motor boat than the sail boat. For the original poster I once again suggest a couple of months of reading about this kind of stuff before plunging blindly into what kind of boat you want or need.

[ranger58sb]

BB2, you can often get a better idea about powerboat fuel consumption once you home in on a specific boat and specific engines. A 35' Carver with gas engines, for example, doesn't necessarily compare closely with a 40' Carver with diesels. But once you know more, you can sometimes find somebody who can give you more accurate info.

Usually fuel consumption is reported in gallons per hour (GPH) at a given cruising RPMs, but if you've got apples and oranges, it usually helps to compute and compare nautical miles per gallon (NMPG)... IF/IF you know approximate speed. And that's sometimes a bit more difficult to come by.

In the meantime, starting with what you've given, and assuming a 35' gas Carver, you could maybe guess approximately 40 GPH total (20 GPH per hour per engine) at approx. 20 kts. (That's a VERY rough guess., but based slightly on our previous 33' gas boat.)

Our current 42' boat with planing hull and twin 450-hp diesels cruises at about 20-22 kts and uses about 26 GPH total (approx. .75 NMPG)... or putters along just under displacement speed at about 7 kts using I think something like 3 GPH total (~2.3 NMPG). But that won't help you much if you're looking at gas.

-Chris

[pelican717]

Best advice I see here is to charter a boat similar to what you think you may want, sail or power. Here in SW Florida there are several charter boat outfits that offer charters with a captain who can teach you how to handle the boat you are on. A great way to learn and be on the water where we all want to be anyway!
Thanks, Robert