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belizebill

belizebill

Senior Member
Joined
Nov 25, 2010
Messages
227
Location
Belize, Central America
Vessel Name
Irish Miss
Vessel Make
36' Marine Trader, D C
Hi all,I will finally be buying my first Trawler.Ive been looking online for a year and have narrowed it down somewhat. I cant get any good answers about GPH,MPG. Im looking at 36' I.G. sedan,Twin 135s/ 36' M.T. sedan 120 single, and I just found a 1983 38' Nova that they dont know what size the twins are. Ive never heard of a Nova, Id hate to fly to Cal. and find shes got 454 buicks in her. Any thoughts ? Thanks Bill
 
Talk to the owners of the boat and ask them thir burn rate. Ask more then one since some may exagerate. They may be telling you a burn rate with a 40 knot tail wind.* If the single doenst have a bow thruster you will probably not be happy with the handling during docking. It can be learned but being a new trawler owner you would probably be happier with the twins. Although you may get an arguement about it here.
 
Looking at 100 online does not compare to looking at 1 at the dock. Last time I bought a boat it involved at least 15 different marinas and probably 40 vessels. The term "walk the docks" is apt. After a few months things like singles, twins, fuel burn, galley up, blisters, teak decks, leaking windows, Taiwan Trawler, *and Nova will start to fall into place.

Make yourself a spread sheet listing your likes, wants and needs.*Add to it condition, hours, mechanical condition*etc. Rank each boat you see accordingly. Good luck.
 
Here is a ROUGH rule of thumb....+/-

Single Lehman 120 is about 2.5 galls/hr @ 1800 rpm

Twin 120s can be about 4 galls/hr.

Remember this is a rough giude. There are lots of specifics that could change these figures.

R.
 
Spread sheets is exactly what Ive been doing (great minds eh?) good advise, Condition,price,Fuel economy is a factor living here in the Western Carribean as I guess anywhere. Not afraid of Teak,its how Ive made my living for the past 30 years.
 
I have a 40' NOVA with twin Volvos. See avatar.
According to "THE BOAT BUYER'S GUIDE TO MOTOR YACHTS AND TRAWLERS", there was no 38' NOVA, only 36, 40, 42 and 44. The 36 may have Volvos too.
NOVAs are made in Taiwan by NOVA Marine as opposed to CHB's etc.
I burn about 6 gph at hull speed.

-- Edited by surveyor1 on Monday 29th of November 2010 08:02:27 PM

-- Edited by surveyor1 on Monday 29th of November 2010 08:07:12 PM
 
Fuel burn is more closely related to the size of the wave you want to pull than to the engines, brand names, size, or whether single or twin. If you are content at hull speed, which for your 36 to 42 ft is going to be 7 to 8 knots, you will get by on 3 to 4 gph. Start going faster and your wave gets taller and up goes the fuel burn.
 
belizebill wrote:

Hi all,I will finally be buying my first Trawler.Ive been looking online for a year and have narrowed it down somewhat. I cant get any good answers about GPH,MPG. Im looking at 36' I.G. sedan,Twin 135s/ 36' M.T. sedan 120 single, and I just found a 1983 38' Nova that they dont know what size the twins are. Ive never heard of a Nova, Id hate to fly to Cal. and find shes got 454 buicks in her. Any thoughts ? Thanks Bill
Click to expand...
THEY DON'T KNOW WHAT SIZE THEIR ENGINES ARE??? Then they probably don't know if they have oil in them. Don't waste your time.

*
 
Usually the rating of the engines will show the style of cruising service the boat was designed for.

A 36 ft boat with 100 hp is going to be really cheap at the Sq RT of the lwl, say 6k for LRC.

Hull speed will double or more , the burn for an extra K or 2.

If the 36 ft boat boasts 350 hp, it was designed as an inshore weekender , the speed will be double the small engined boat 15K but the fuel burn will be 10-15 times higher.

On unusual boats , where you cant simply ask owners , a quick math will work.

Find the vessels displacement , that is how much it weighs (not the USCG "tons" which is volume).

Divide the weight in pounds by 2240 for the displacement in tons.

Slow cruise will cost 2 or 3 hp per ton, so multiply the tons by 3.

Then divide that number by 16 for a diesel or 12 for gas.

This will give a rough GPH at normal cruise.
 
ralphyost wrote:

Here is a ROUGH rule of thumb....+/-

Single Lehman 120 is about 2.5 galls/hr @ 1800 rpm

Twin 120s can be about 4 galls/hr.

Remember this is a rough giude. There are lots of specifics that could change these figures.

R.
Click to expand...
Amen to this. *If you need to know more than this, then you are just being "geeky" about fuel burn or you are in over your head(financially) if you are sweating every ounce of fuel burned.

*
 
My main concern about fuel usage is if I have to add tankage to cruise in the third world where I live and not have to be looking for "good" fuel all the time. Bill
 
Sorry Bill if I came off condescending. I guess my statement was a generalization from a coastal type...
 
So what kind of range are you looking for?* *


*
I just posted a long reply under Hi! Newbie as his is sort of looking for boat with good range, 3000 to 4,000 NM.*
 
Baker wrote:If you need to know more than this, then you are just being "geeky" about fuel burn or you are in over your head(financially) if you are sweating every ounce of fuel burned.



*
Click to expand...
Baker, that's not like you.* Are you sure you are getting enough bulk in your diet?
smile.gif


*
 
I was wanting around 1500nm,I can bypass Mexico,(from Key West) that way and come up or down the Yucatan channel after fueling in Belize or Havana,depending going North or South.Bill
 
I am not so much concerned about the price as I might be about range as I would like to fill up in Seattle and not have to fill up in Canada. I am not sure what the price is in Alaska? Moat of the commercial run straight through Canada as they have to much gear stuff to clear canadian customs?

So what kind of boat are you looking at as that is a big factor as to fuel use and range?
 
Yea,I wanted to stay around 36', Im adding a nother 100' of dock so I can get 4'. We can be preety shallow around here. Id love to have a larger boat but draft is also a concern. Bill
 
FF wrote:

Usually the rating of the engines will show the style of cruising service the boat was designed for.

A 36 ft boat with 100 hp is going to be really cheap at the Sq RT of the lwl, say 6k for LRC.

Hull speed will double or more , the burn for an extra K or 2.

If the 36 ft boat boasts 350 hp, it was designed as an inshore weekender , the speed will be double the small engined boat 15K but the fuel burn will be 10-15 times higher.

On unusual boats , where you cant simply ask owners , a quick math will work.

Find the vessels displacement , that is how much it weighs (not the USCG "tons" which is volume).

Divide the weight in pounds by 2240 for the displacement in tons.

Slow cruise will cost 2 or 3 hp per ton, so multiply the tons by 3.

Then divide that number by 16 for a diesel or 12 for gas.

This will give a rough GPH at normal cruise.
Click to expand...
This method was right on for my boat.* This calculation is very close to actual fuel burn at slow cruise.

*
 
Hiya,
** Mr bbill.* Where are you located in Belize?* I have a slight familiarity with Caye Caulker and Ambergris...
 
Hi Belizebill, for what its worth I have an IG 36 with twin Lehman 120's and I think 4gall/hour is about right. I used to have a 34 Clipper with single 120 Lehman and found both boats cruised at the same 8knots on 1800rpm, but the single def used less fuel.The Clipper had a bow thruster which for me was a must and it was great in all but really strong cross winds.

On balance I like the twin engine set up because of the greater control it gives(me anyway) in close quarter manouvering in strong winds.

I would not worry to much about the fuel use, IMHO it is far more important to ensure the boat and engine are in good condition, get that wrong and you can be looking at some big bills,find a good surveyor, it's money well spent.

Good luck.
 
FF wrote:

Usually the rating of the engines will show the style of cruising service the boat was designed for.

A 36 ft boat with 100 hp is going to be really cheap at the Sq RT of the lwl, say 6k for LRC.

Hull speed will double or more , the burn for an extra K or 2.

If the 36 ft boat boasts 350 hp, it was designed as an inshore weekender , the speed will be double the small engined boat 15K but the fuel burn will be 10-15 times higher.

On unusual boats , where you cant simply ask owners , a quick math will work.

Find the vessels displacement , that is how much it weighs (not the USCG "tons" which is volume).

Divide the weight in pounds by 2240 for the displacement in tons.

Slow cruise will cost 2 or 3 hp per ton, so multiply the tons by 3.

Then divide that number by 16 for a diesel or 12 for gas.

This will give a rough GPH at normal cruise.
Click to expand...
FF


I think you missed the mark a little on fuel consumption for your hypothetical 350 hp vessel Fred. For example, my 420 hp single engine boat burns only twice as much at 15 knots, compared to 8 knots. Not 10-15 times the slow cruise. I get just over 2 mpg (assuming no tidal effect), at 8 knots, and 1 mpg at 15 knots. This is factual, not incorrect theory.

*
 
15Gph times at the very best 20Hp per gal is 300HP

If you propped and ran the boat to use the last 120 hp (or more likely 160hp) the burn would be up another 8-10GPH.and perhaps another 2K -4K faster.

A "rule of thumb" is designed to give a rough estimate of performance , so one can understand the concept the designer had in mind for the build.

420 hp, in a 36 FT boat was built to run between marinas , NOT CONTINENTS.

1500 miles of range would be really hard, due to fuel weight and volume.
 
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