Fuel Efficient Trawler and Electronics

[Cruising Roo]

Hi all. Very new and just doing my “due diligence” of living aboard a motor boat. I am from the south of Australia. To that end, may I ask you experience sailors the following;
1. What is a fuel efficient trawler hopefully not much more than 45 foot, and
2. Are the trawlers the most efficient option. I certainly am not in any hurry
3. Are single engine boats more efficient and is there anything I should be aware of in this regard
Let me throw in another question if I can. My plan is to stay in Australian waters and frankly see no need to be too far off the coast so what would be the minimum electronics. Is a radar that important. I had a small boat with radar which was good for steaming at night but I am planning to only steam in daylight hours. Thank all
Darren

[Galumay]

1.) See if you can find something with a Gardner or John Deere engine, very reliable, simple, and you should get close to 1L/nm. Avoid anything with a Detroit, Cummins are OK.

2.)Trawlers per se are not the best option if you mean actual ex-commercial craft, if you just mean a larger single screw displacement power boat, they can be quite efficient.

3.)Single versus twin is one of those questions there is no right or wrong answer. With a well maintained, quality, single engine you save 50% on running maintenance costs, and it will likely be more fuel effecient on a like for like basis. On the other hand 2 engines gives you redundancy if something goes wrong with one.

EDIT - I would also consider power cats, if you can find a power cat with small economical diesels because you get a lot of advantages IMO.

I dont have radar, they are handy for more than just night time, watching storms in the daytime and working out where and how fast they are travelling is useful. If you are in mobile range then you will have access to rain radar anyway on phone or tablet/laptop.

Starlink gives us access to internet when out of mobile range (nearly all the time given our remote location) so we can still access rain radar and full weather.

Minimum electronics I would be happy with is a good plotter/sounder and integrated Autopilot.

As I said in your other thread, at some point you will be steaming outside daylight hours, so you just need to be comfortable with the gear you need to do that.

[rslifkin]

Twins will burn slightly more fuel in an equivalent boat, but typically not more than 10 - 15 percent more. Twins will also cost more to maintain, but not double. They're often 2 smaller engines, so individual maintenance items get cheaper despite having twice as many.

Fuel wise, depending on hull form and engines, a 40 footer doing 7 kts will typically get somewhere in the range of 2.5 and 3.5 nautical miles per gallon (assuming diesel power).

[mvweebles]

Single vs Twins is less important than speed. If you stay under 1.2 S/L, most boats are pretty economical. That said, single, full-displacement hulls tend to be 15%-20% more efficient than a twin with semi-displacement hull run at same speed. I used to deliver trawler yachts - two examples come to mind: A Nordhavn 57 from Los Angeles to Florida (via Panama Canal). 4500 nms and burned 3000 gals diesel at 9-kts average. 6gph (2.5 l/nm. Several Nordhavns have circumnavigated to give some idea of the capability of these boats, but it comes at a price.

Second example is a Willard 40 from Los Angeles to La Paz MX, about 1000 nms. Burned around 190 gals - 7.2 kt average. Over 5nm/gal (0.75 l/nm)

A friend's very nice and expensive 52-foot Power Cat cruises at 18-kts and burns 36 gph (7.5 l/nm) which is relatively economical. At displacement speed of around 8-kts, he burns 8 gph (3.8 l/nm). Older monohull motoryachts with sufficent power to run 18-20 kts could easily burn 50-60 gph (close to 13 l/nm).

But I think fuel economy is a secondary concern. While a fast boat can be throttled-down for economy, faster boats tend to have smaller rudders and do not handle as well at displacement speeds. Of course, a displacement speed boat cannot be made to go fast if needed so it's a tradeoff. Finally I'll add that vast majority of trawler owners state that fuel is not their biggest expense - usually 3rd or so behind moorage and annual maintenance (same for sail). But if you plan on going long distances, fuel will of course become a larger concern.

[valhalla360]

If you are worried about fuel, go slow. Even a high powered planing power boat can double or triple the miles/gal by slowing down to 5-6kts.

I see a lot of people buy trawlers than push them to 8-12kts (depends on length and hull design), pushing a huge wake and then getting lousy efficiency. It takes a lot of fuel to make a big wake but the boat doesn't go much faster.

I do like motoring with a catamran. They can often go a bit faster (all else being equal) without making a big wake.

[Simi 60]

Originally Posted by Galumay

1.) See if you can find something with a Gardner or John Deere engine, very reliable, simple, and you should get close to 1L/nm. Avoid anything with a Detroit, Cummins are OK.

Gardner are good but try getting parts or work done and you might second think it - I certainly did

JD? Have yet to see a boat in Oz with one

Detroit? Plenty of people swear by them and they have the runs on the board

Cummins? The 855 Cummins is one of the best engines ever made and why so many commercial trawlers have them.

[Cruising Roo]

WoW and holy bat *****. So much awesome info so OMG…thank you
Gulamay, I will be paying far more attention to your advice as you clearly you have heaps of experienced.
1. When I mention trawler, I am meaning a displacement hull only because I am not in any hurry and as you mentioned, they tend to be more fuel efficient. My brother is rich (unlike me) and has just purchased a huge planing boat. I could not afford the fuel he uses just to warm up the engine let alone go anywhere!!
2. In terms of a power cat, I agree (from my limited “virgin” knowledge) would be the ultimate in so many ways but they are much harder to find I think and I think will be too expensive for me. The ones I have seen on line are upwards of $700k second hand but dreams are cheap. Your boat looks bloody amazing.
3. In terms of daylight steaming, I have done a lot of calculations between ports etc up the east coast of Australia and I am in no position to question your comment. I have calculated so many posts, distances boat speed etc but of course there are so many other factors in play. I do not have a major aversion to night time steaming but in the thousands of hours (yes thousands) I spent at sea, I know enough to know that I know nothing and this is my “safety measure”. That is, I am far from a “know all”; never have been and never will be especially at sea which is why I really appreciate all the advice
Thanks rslifkin. Whilst I have an elementary understanding of the S/L, I am but a simple man and your assessment means more to me.
Mvweebles… I think it fair to conclude you “know a little bit about boating” Yes ALL of the costs of doing what I am doing need to be considered and things like moorage are just one of the factors against a multi hull. Despite all the huge advantages of a motor cat as suggested by Gulamay, all the costs need to be considered in relation to the type of cruising I would like to do. In concluding “Bloody Awesome Advice” all…thank you

[Galumay]

Yep power cats with suitable engines are hard to find and quite expensive.

I understand your dilemma, we spent probably 2 years looking for a displacement monohull power boat with a Gardner or John Deere for economical reliable cruising of the NT coast.

Right at the end of our search we pivoted to a sailing catamaran, because it met our criteria for a tropical coastal cruising boat better than any mono. Although I have extensive ocean sailing experience when I was younger, my wife had very little sailing experience and we had owned various power boats for the last 30 years here so a sailing vessel was just not on the radar originally.

Given your issues with sailing the sail cat is not an option, and as we know, hard to find a suitable power cat in a suitable price range.

I think if you keep looking you will find something suitable, another thing to be clear about is which hull materials you would be comfortable with. Personally I prefer fibreglass or steel, dont mind Aluminium, avoid timber. But all have their advantages and disadvantages.

Another consideration is age of the boat, its getting increasingly harder to insure older boats in Australia so thats worth bearing in mind too.

[rslifkin]

Keep in mind that while a semi displacement hull isn't as efficient, the difference is often not huge in the real world. Many FD hulls aren't as efficient as they could be (some like Willards are an exception and more efficient than most). And SD boats are often lighter, so that makes up for some of the hull shape inefficiency, especially once you slow down to about a knot below hull speed.

[Fore and Aft]

Simi 60 is right, a client of mine has a Gardner diesel and getting some parts and being serviced is a bit of a trial.
If you are looking at converted trawlers lots of them are getting fairly old and are needing serious maintenance. Not sure how comfortable I would feel circumnavigating Australia with a vessel held together with 50-year-old fastenings.
Simi 60 I have surveyed three boats with John Deere diesels, they are pretty rare in the marine industry here.
Cheers

[Galumay]

I have Yanmars and some major parts are now unavailable (a bit over 10y old engine). Gardners are pretty simple, servicing is something any diesel fitter let alone competent amateur, could do. Would still be my first choice in a single engine power boat, but I understand why others would disagree.

Agree about converted trawlers, also they are rarely economical as they run bigger mains for work and huge gensets for snap freezers etc.

Probably more John Deeres around than people realise, we looked at about half a dozen when we were searching, but they are certainly less common than crappy Detroits or Cummins/Cats/Perkins/Ford Lees etc

[Simi 60]

I know several Gardner owners.
One has been searching for a heat exchanger for well over a year now.
I can get a brand new heat exchanger for my 855 Cummins in under a week direct from Cummins China

Another I know who was based in the Whitsundays had to get a mechanic up from Brisbane to do work on his.
Id hate to have an issue with one somewhere that was actually remote.

[Galumay]

Ok, well i think we are dragging this off topic now, so I will just agree to disagree.

[Simi 60]

Originally Posted by Galumay

.

Agree about converted trawlers, also they are rarely economical as they run bigger mains for work and huge gensets for snap freezers etc.

We are a converted trawler
60 ft, 65 tonne and we consistently burn 15lph including Genset usage for a 7.5knot cruising speed.

Whilst the 855 Cummins is bigger than a 6lxb gardner we only use about 120hp at a fast idle.
The 6lxb would be running at full noise and using marginally less, but working hard continuously.

Our slightly smaller sister ship has a 6lxb so I know this to be true
And when ours was given a new engine during her rebirth the previous owner looked at the 6lxb but thankfully decided against it.

[StuM]

If you are not familiar with it, there is a "sister forum" that is aimed more at your interests:


https://www.trawlerforum.com/forums