Trawlers vs. Cruisers
- Thread starter AL8156
- Start date
Currentsea: no diesel that I know of has a cylinder shut down feature probably because it is unnecessary.
Diesel engines use the same block to produce a wide range of HP ratings, e.g. 150 to 400 for the 5.9L Cummins that is also used in the dodge pickups. A 40’ boat probably needs 50 to run at 7 kts in calm conditions. The boat doesn’t know if the engine producing the 50 HP is a 120Hp Ford Lehman or a 400 HP Cummins.
50 HP requires about 2.5 gal per hour. So when you run using 50 hp from a 400HP engine you are consuming the same 2.5 GPH as you would with a 120 Max HP engine commonly used in “trawlers”. The engine likewise doesn’t know if the salesman called the boat a “trawler” or express or ACMY, it is happy to produce 50 HP regardless.
Don’t succumb to the baloney that diesels don’t like to run slow. There are a lot of myths surrounding diesels but most don’t stand up to reasonable scrutiny. Consider the Cummins I referenced earlier. In a dodge pick up that engine would be happy producing 50HP to cruise a flat highway forever and nobody would question that it was being run too easily. Put the same block in a boat and all the “diesel” experts come around claiming terrible things will happen because it is in a boat producing the same HP. Every engine does require being run at proper operating temperature but that is what thermostats are for.
It is very worth noting that heavy duty rated diesels, “continuous duty” are commonly a engine derated by more than 50% or so of max rating. The less work they do the longer they will do it.
Diesel engines use the same block to produce a wide range of HP ratings, e.g. 150 to 400 for the 5.9L Cummins that is also used in the dodge pickups. A 40’ boat probably needs 50 to run at 7 kts in calm conditions. The boat doesn’t know if the engine producing the 50 HP is a 120Hp Ford Lehman or a 400 HP Cummins.
50 HP requires about 2.5 gal per hour. So when you run using 50 hp from a 400HP engine you are consuming the same 2.5 GPH as you would with a 120 Max HP engine commonly used in “trawlers”. The engine likewise doesn’t know if the salesman called the boat a “trawler” or express or ACMY, it is happy to produce 50 HP regardless.
Don’t succumb to the baloney that diesels don’t like to run slow. There are a lot of myths surrounding diesels but most don’t stand up to reasonable scrutiny. Consider the Cummins I referenced earlier. In a dodge pick up that engine would be happy producing 50HP to cruise a flat highway forever and nobody would question that it was being run too easily. Put the same block in a boat and all the “diesel” experts come around claiming terrible things will happen because it is in a boat producing the same HP. Every engine does require being run at proper operating temperature but that is what thermostats are for.
It is very worth noting that heavy duty rated diesels, “continuous duty” are commonly a engine derated by more than 50% or so of max rating. The less work they do the longer they will do it.
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CS, while a large MY styled boat will achieve good economy by slowing down, it will not even be close to the economy of a true trawler. i get just about 1nmpg at 9kts which is pretty good for a 50k lbs 53 footer but a true tralwer of the same size can probably get twice as much because of the more effcient displacement hull. to put things in perspective, my fuel cost per mile under half of what they used to be with my previous gas 37 express ...
many folks have done th egreat loop with boat up to 60 to 70'... i think 20 or 21' is the limiting height somewhere near chicago. not sure about the "side trips", i think lake champlain has a lower limit, but afaik it's all height, not loa
many folks have done th egreat loop with boat up to 60 to 70'... i think 20 or 21' is the limiting height somewhere near chicago. not sure about the "side trips", i think lake champlain has a lower limit, but afaik it's all height, not loa
true however if they are not smoking of dribbling fuel there is no problem. Remember the injector pump detrermines fuel delivery more than orfice size. They also lack turbochargers and aftercoolers.
I suspect that your experience is of seeing many diesels die of overwork but none dieing of under work.
I suspect that your experience is of seeing many diesels die of overwork but none dieing of under work.
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I don't have a problem running my 450's at low rpm for fuel saving, however I don't get the handling capabilities, or the ride I want , with our motoryacht hull. The trawler hulls, I think give a better ride at those slow speeds, however that is just the way ours handles.
I have a 36 foot semi displacement hull, fuel economy is not the only issue. During a fishing tournament there were 8 foot seas, I went out at 6 - 8 knots and although it was not exactly comfortable my boat performed well. A friend of mine with a 40 foot viking went out and the rough seas spun his boat around so he came back in. Last year there was a stiff wind against an out going tide at a different inlet. 50 footers were turning around and would not go out. I just took my time and easily went through the inlet. With the right engine semi displacement hulls can cruise 18knts +. In the event of a storm while out on a long trip I would rather be in a semi displacement hull than a planning hull. Everyone has to make there own choices for their own desires.
boathandler
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Reminds me of a sailboat called a Lancer, advertised as being able to go fast enough under power to ski behind.
Grady Wahoo
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There's a very good article written by Chuck Husick on the subject of true trawlers (versus hybrid trawlers). Here is a relevant quote:
"The quest for speed on the water has created a market for boats with trawler-type appearance and accommodation but capable of operating at three or more times hull speed. The availability of lightweight diesel engines in the 200- to 600-hp power range has allowed for boats that look like trawlers but have planing hulls. These vessels are popular with those who need to get to their destinations rapidly. The greater speed achieved by these hybrid trawlers is paid for in a number of ways. High-power engines are costly. Running time at maximum power is restricted, both by engine operating time limits and their substantial appetite for fuel. Planing hulls' performance can be very sensitive to vessel weight. The need to limit structural weight may increase construction cost. Fuel and water capacity may be significantly less than is common in the traditional trawler. Although these boats can operate at true displacement speeds, their behavior at such speeds is often inferior to that of pure displacement-hull vessels. In addition, the superstructure of a planing trawler creates more aerodynamic drag than the more streamlined designs of other planing-hull boats. Although this hybrid design appeals to some yachtsman, this type of boat has by no means superceded the full-displacement trawler."
For the rest of the story titled "The power/displacement trade-off":
http://www.oceannavigator.com/article.php?a=189
"The quest for speed on the water has created a market for boats with trawler-type appearance and accommodation but capable of operating at three or more times hull speed. The availability of lightweight diesel engines in the 200- to 600-hp power range has allowed for boats that look like trawlers but have planing hulls. These vessels are popular with those who need to get to their destinations rapidly. The greater speed achieved by these hybrid trawlers is paid for in a number of ways. High-power engines are costly. Running time at maximum power is restricted, both by engine operating time limits and their substantial appetite for fuel. Planing hulls' performance can be very sensitive to vessel weight. The need to limit structural weight may increase construction cost. Fuel and water capacity may be significantly less than is common in the traditional trawler. Although these boats can operate at true displacement speeds, their behavior at such speeds is often inferior to that of pure displacement-hull vessels. In addition, the superstructure of a planing trawler creates more aerodynamic drag than the more streamlined designs of other planing-hull boats. Although this hybrid design appeals to some yachtsman, this type of boat has by no means superceded the full-displacement trawler."
For the rest of the story titled "The power/displacement trade-off":
http://www.oceannavigator.com/article.php?a=189
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Old Salt
I left you a private massage.
Using two 350 HP turbo diesels to push a boat at hull speed needing only 50 HP to do is not doing your turbo diesels any favors. I find there is always some truth to myth.
<Grin>
IMO
I left you a private massage.
Using two 350 HP turbo diesels to push a boat at hull speed needing only 50 HP to do is not doing your turbo diesels any favors. I find there is always some truth to myth.
<Grin>
IMO
oldfishboat guy:
WOW! Thanks, Bud! She was great! I really liked what she could do with her bare feet!!
Private mEssage? Awww!
I can see I received one, but I can't access it. Clicking on my PM Inbox only brings up the "Forums Menu".
You can e-mail me at
xxxdenny_sawyeratdccnet.com
if you delete the x's and "at" and add the "at sign" in place of the "at".
OS
I'm a future new boater (a few years away). Getting new ideas all the time from the forum. I love the look and benefits of "fast trawlers" Seems to be what I may like. Question for those who have this boat, particularly with hardtop, is the boat too enclosed? Many (back cove 29) seem to have center window that opens, but are there times when there's too little open/fresh air? Thanks, Elliot
There are few 'fast trawler' at least in the traditional tri cabin configuration. Boats such as the Eastbay (pictured in the link from Grady Wahoo) are far from being a trawler. Builders of this style such as Sabreline don't even call them trawlers. The style is called an 'express'. Depending on power, they can max in the low 30kt range & cruise all day in the mid 20s. Below the waterline they are little different from a SF.
fth232, the Back Cove is a nice boat. Built by the same people as Saberline. The Back Cove is to Saberline like the Bently is to a Rolls Royce. You might find a lightly used Saberline for the price of a new BC. That opening center window is a huge plus for keeping the helm area cool. The BC may also have hatches in the roof of the helm like the Saberline as well as opening side windows. For something similar in style & speed, about the same finish as a Back Cove but not as nice as the Saberline look at the Albin 28TE.
fth232, the Back Cove is a nice boat. Built by the same people as Saberline. The Back Cove is to Saberline like the Bently is to a Rolls Royce. You might find a lightly used Saberline for the price of a new BC. That opening center window is a huge plus for keeping the helm area cool. The BC may also have hatches in the roof of the helm like the Saberline as well as opening side windows. For something similar in style & speed, about the same finish as a Back Cove but not as nice as the Saberline look at the Albin 28TE.
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Spotted this one last summer on the St. Lawrence river entering the Seaway. Vicem 65 Motoryacht. Being delivered to new owner in Chicago.
http://www.vicemyacht.com/v65/
Quite an extra ordinary motoryacht and fast too! Twin 960 BHP Turbo Diesels. If you're looking to drop a couple mil on a yacht this would be a nice acquisition.
http://www.vicemyacht.com/v65/
Quite an extra ordinary motoryacht and fast too! Twin 960 BHP Turbo Diesels. If you're looking to drop a couple mil on a yacht this would be a nice acquisition.
Grady Wahoo
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They featured a Vicem on PMY's tv show. Nice looking downeast lines considering the origin. Istanbul I believe...
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Ayup. Very nice craftmanship. The delivery captain and crew had a few observations such as all square corners on the furnishings. A lot of little things like no towel racks or cup holders, things we all take for granted. The door from the cockpit to the saloon didn't have a stop/catch and bounced off of the marble bbq countertop and broke the corner off.
We were crossing Lake St. Francis at 25 kts when she went blowing by us like we were sitting still. I wouldn't want to guess how much fuel they were burning at what the captain said was 38 kts.
