Outboard powered Trawlers?

markpierce said:

I don't like bouncing over waves. Prefer to plow through them.

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The question of what the cruiser with outboard mounted being a Carver. It is. A 32 foot model. It is recalled that they came as twin powered gas as standard but single 454 gas seems to come to mind as well.
The demonstrated concept is worth consideration when you are matching the fuel burn of the outboard(s) vs: the inboard(s). Ease of maintenance for one.
There are any number of conversions here in Southeast Alaska. The newer Mercury, Honda, and Yamaha large HP units are trouble free for the most part. Fuel burn is respectable for the speed/burn ratio.
Most of the conversions here are mounted on 26-32 foot rigs that were designed for some speed, (26' Tolly-24'/28' Reinell-28' Glasply as example) These conversions were made on I/O and straight shaft.
Have to agree that in the majority of the conversions the maintaining of a respectable level of speed is the goal. Contrary to we slow conventional "Trawler" boats.

Perhaps the concept as we view "Speed" would be better met with the use of "High Thrust" geared 9.9 Yamaha(s) or "High Thrust"15 HP Yamaha(s) on SD displacement
hulls that then would reflect more the traits of current mode of power. At about $3500.00 for a new Yamaha "high thrust"9.9. A,couple replacing a straight inboard would be somewhat cheaper as a replacement. Of course there are the added cost of a mounting bracket about $2-4,000. These OB's now come with electric remote controls making the installation a snap. With the original engines out of the picture, additional fuel tanks, storage, water tanks, what ever, can be considered.
Again, those who I am aware, are content and pleased with making or purchasing such a conversion.
The Carver viewed is a prime example in my opinion.
Regards,
Al-Ketchikan (Bridge to Nowhere) Alaska

To the OP: No, those definitely aren't recreational trawlers but that doesn't mean they couldn't meet your boating needs.

Most of the newer OB and IO powered boats have the same hassle.

Although it would be fairly easy to do with an OB the engine is not built to be lifted and is left immersed 100% of its life.

Sure it works fine for commercial fish guys and tour boats as they operate a few hundred days a year , so wear out the engine in 2-3 years before ir dissolves.

Most rec boats would dissolve the outboards or IO drive with only 200-300 hours a year of operation.
Remember many trawlers are 30-40 years old and are on their first engine.

There are low speed leg drives that are built for 3rd world use , that do rotate up and out and would solve the hassle. Many are aft deck mounted so a diesel, air or water cooled can be chosen , depending on local supply conditions.

CPseudonym said:

Correct me if I'm wrong Rustybarge but can you acquire diesel outboards in Ireland?

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Unfortunately the EU have imposed emission controls that are so strict on Diesel engines that you would have to invent an engine that ran on water to get it certified.

But there is a supplier of Reconditioned Yanmar diesel outboards to the oil supply industry Scotland where there are restrictions on using volatile petrol in your OB.
I seriously considering this until I got a quote : 28 hp £12k plus 20% tax! and the bigger model thirty something hp £18k the guy told me the reconditioning kit from Yanmar in Japan was over £5k just for the bits.

There is a guy on the BD forum trying out the Chinese Runsun 40 hp diesel at the moment; I think it's about au$8k, but I know it took over a month to get a replacement impeller form china!
Diesel outboard - Boat Design Forums

My post on the same forum is about bolting a VW Diesel engine to an OB leg!
Converting an Outboard to Diesel. - Boat Design Forums

deckofficer said:

I think Richard was getting about 4 nmpg on that passage. The most efficient outboard I know of isn't quite a trawler, has a much higher cruise speed of 16 kt but does get 4 nmpg at that clip. Slow down to 14 kt and sip at 7 nmpg.

MC30

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That's an interesting Cat.

Just for reference my 25' by 8' Cheetah cat that weighs 1.5 tons,similar to the one in my little photo ( I'm building the wheelhouse at the moment) gets about 4.5 mpg at 15kts on twin 40hp OB's.....worse than they are stating for their 2.5 ton boat!
Cheetah Marine LLP

HopCar said:

Hi Rusty, I don't think that's the boat for cruising but I like the idea of using an outboard to power a trawler cruising boat.

I'm going to cause some thread drift sorry. One of our members just completed an Atlantic crossing and is in Castletownbere. If you're any where near there you might want to stop by and say hello.
You can see where the boat is here: https://share.delorme.com/Dauntless

I see that Richard came up in the conversation while I was typing.

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I'm totally amazed by Dauntless. I've never be more than a few miles offshore; when the land disappears over the horizon I start to panic .:lol:

I'm Right in the middle of Ireland, and I don't know Cork very well unfortunately.

Cork people are know all over Ireland for being the best at everything:
Cork is the best place in the world
Everything in Cork is much better than any where else
Everyone in Cork is much more intelligent
..in fact Cork IS the premier place in the World: full stop.:lol:

Apologies to the forum: my posts are being moderated, so there is a delay before they appear.

3 or 4 of my posts have disappeared into the 'ether': I will wait to see if they reappear !

Our Nimble Nomad trawler is OB powered with a 1991 Honda 45hp. It is trailerable although I have not done so in many years. When not in the water it resides on a lift.

Scary said:

A 20/21 deg planning hull is not a good choice for trawler speeds in anything more than flat water. They are very sea kindly on plane at 20knts and up. Slow speed they pitch and roll in rough conditions. Lose power and they swing beam to and roll. I cruised a 28' 21 deg 10' beam boat for over 10 years. You are pretty much stuck with the 1.4 mpg. A well designed outboard is a good choice, however very pricey when compared to a car block marine outdrive. Aluminum cats can do both go fast and slow. Probably a better route. They can be full displacement run fast with lower power and are very stable at slow trawler speeds. Think Glacier Bay.

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Phew, trying to catch up with the posts!

You have confirmed what I was worried about, but there seems to be an exception to every rule: the Botnia targa patrol boats is used by the Police and customs and is considered exceptional at sea, and is also dead steady on the river at displ. Speed.(but is has an I/o with Volvo 300hp) but only weighs 3.5 tons, 27': http://www.targa.fi/boats/251

It's a deep vee but can plane at just over 10kts!

Here's the hull:

manyboats said:

Wth 20 degrees deadrise and the engines all the way aft a boat will trim very bow high and be very inefficient.

Not trawler like at all.

At a knot below hull speed an OB will power a trawler but in rough going the prop may come out of the water.

I think it's hard to declare any OB boat a trawler but perhaps a very unusual one could qualify. Example ... An OB powered Albin 25 w the lower unit several inches deeper than usual I'd be inclined to call a trawler.

Outboards are high rpm and don't have low enough gears for an appropriate diameter propeller. If they did 15hp would be plenty on the Albin. IMO

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I have a little standby Tohatsu 6hp extra long shaft OB with a big fine pitch prop and it pushes my cat along at about 6kts in all conditions, so if the OB leg is long enough it will stay in the water in the chop.

Nimble1 said:

Our Nimble Nomad trawler is OB powered with a 1991 Honda 45hp. It is trailerable although I have not done so in many years. When not in the water it resides on a lift.

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Now that's a proper looking trawler!
I really like the Rossbourough as well.

I'm only interested in coastal cruising, and internal volume is important as I will be cruising around the med and living aboard.

32' is about the minimum size, and most marinas have length bands that start at 32', then 40' etc, so a 32' fits in nicely in the bottom price range.

IMO, one of the definitions of a trawler is that it does well at slow speeds in moderate seas (pick your sea state). To do this at slow speed it needs to be able to punch through seas, not bounce off the waves. Simply, that requires significant weight. Nothing wrong with riding on plane through the tops at 12 to 20 knots like a Downeaster or a Cat, but that's not going slow.

As to whether an outboard can get the same efficency as a diesel, you have to take the same boat with the same load displacement at the same hull speed to make that comparison. There is a 34' 28,0000 lbs. displacement trawler called Briney Bug that claims a 16 mpg consumption at 4 knots and 10 mpg at 5 knots. Doubt you could replicate with an outboard simply because on the lack of propeller diameter and fuel inefficiency of outboards at slow speeds. The above aside, I'm sure you can take a 28' +/- hull displacing 7,000 lbs. and push it along at hull speed at 4 to 5 mpg.

Ted

Rustybarge said:

Hi All and Greetings from Ireland,

I've been lurking here for a while looking at the posts; very interesting and informative.

I'm interested in a trawler, BUT buying a 30 year old model does not appeal to me because of the potential of a financial melt down if the engines blow up. To me it's the same question as "How much is a 30 year old truck worth?" When you come to resell your boat.

I was looking at these outboard designs in alloy which would come in at 'budget' brand new, the complete hull/superstructure ready welded at about €2k/ft; the interior fitted out as a home build. Just hang the outboards on the transom and go!

32', 3 tons, 300hp.......

Are these really trawlers?.........

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You can call them what you like or you can argue about the name, it's not important. What is important is, will the boat you are considering buying meet your needs?

I have no idea what "€2k/ft" means in dollars but when you mention "Just hang the outboards on the transom and go!" I have to wonder if the price does not include the outboards and if you have considered the price of two relatively high powered outboard motors and the cost of installation including a means of steering and controlling them.

There are hundreds, perhaps thousands of trawlers on the market, new and used. If the thought of buying a thirty year old boat bothers you, buy a twenty year old boat. Or a ten year old boat. Diesel engines as used in boats typically run thousands of hours before major service. Not so gasoline engines and especially high revving outboards. Diesel is safer and more efficient than gasoline.

Another advantage to buying an existing trawler is that you can take it for a sea trial and see how it performs. Buy a hull and add your own engines and you have what you have, good or bad.

O C Diver said:

IMO, one of the definitions of a trawler is that it does well at slow speeds in moderate seas (pick your sea state). To do this at slow speed it needs to be able to punch through seas, not bounce off the waves. Simply, that requires significant weight. Nothing wrong with riding on plane through the tops at 12 to 20 knots like a Downeaster or a Cat, but that's not going slow.

As to whether an outboard can get the same efficency as a diesel, you have to take the same boat with the same load displacement at the same hull speed to make that comparison. There is a 34' 28,0000 lbs. displacement trawler called Briney Bug that claims a 16 mpg consumption at 4 knots and 10 mpg at 5 knots. Doubt you could replicate with an outboard simply because on the lack of propeller diameter and fuel inefficiency of outboards at slow speeds. The above aside, I'm sure you can take a 28' +/- hull displacing 7,000 lbs. and push it along at hull speed at 4 to 5 mpg.

Ted

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I've got a sneaking feeling you're right, a planing boat by definition planes on top of the water, not through it.

There something very reassuring about the steady beat of a diesel; especially The older models with no electronic gizmos, I like a diesel with a manual fuel cut off that leaves the diesel running without battery power.

rwidman said:

You can call them what you like or you can argue about the name, it's not important. What is important is, will the boat you are considering buying meet your needs?

I have no idea what "€2k/ft" means in dollars but when you mention "Just hang the outboards on the transom and go!" I have to wonder if the price does not include the outboards and if you have considered the price of two relatively high powered outboard motors and the cost of installation including a means of steering and controlling them.

There are hundreds, perhaps thousands of trawlers on the market, new and used. If the thought of buying a thirty year old boat bothers you, buy a twenty year old boat. Or a ten year old boat. Diesel engines as used in boats typically run thousands of hours before major service. Not so gasoline engines and especially high revving outboards. Diesel is safer and more efficient than gasoline.

Another advantage to buying an existing trawler is that you can take it for a sea trial and see how it performs. Buy a hull and add your own engines and you have what you have, good or bad.

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Thanks for your suggestions.

That's a very good point; how good are those alloy OB trawler style boats?
It's called a crab boat which to me means it planes out to the crab pots at 20 kts then floats around lifting the pots, then rushes off to the next place and repeats the process: hardly chugging along at displ speed!

I am curious about the whole outboard thing -- for Seaweed. Purely speculation however:

She takes 8hp according to vicprop to push her at hull speed.

However, a motor run at half throttle will use less fuel? So, if I went with a 15hp, theoretically, would that be better?

Seaweed will not plane -- she's got a displacement hull and even with the 260hp gasoline inboard beast she came with, Seaweed cannot get out of her own way. During her sea trial, pre-purchase, with full throttle and the trim tabs still installed, she would not get up and go. And that was before I added my Stuff.

[The new diesel is progressing well, but I'll tell you, the thought of an auxiliary power (outboard) surely has piqued my interest.]

I did explore this at 3k a 9.9 can be had. Plus mounts, new prop, spare electric start -- give or take.

Anyway, in the eventual Perfect World scenario, would a 9.9 be a better option than a 15? I do understand a 9.9 can be turned into a 15 however that would negate the 5 year warranty on these things so is not an option in my view.

What say the experts?

janice142 said:

I am curious about the whole outboard thing -- for Seaweed. Purely speculation however:

She takes 8hp according to vicprop to push her at hull speed.

However, a motor run at half throttle will use less fuel? So, if I went with a 15hp, theoretically, would that be better?

Seaweed will not plane -- she's got a displacement hull and even with the 260hp gasoline inboard beast she came with, Seaweed cannot get out of her own way. During her sea trial, pre-purchase, with full throttle and the trim tabs still installed, she would not get up and go. And that was before I added my Stuff.

[The new diesel is progressing well, but I'll tell you, the thought of an auxiliary power (outboard) surely has piqued my interest.]

I did explore this at 3k a 9.9 can be had. Plus mounts, new prop, spare electric start -- give or take.

Anyway, in the eventual Perfect World scenario, would a 9.9 be a better option than a 15? I do understand a 9.9 can be turned into a 15 however that would negate the 5 year warranty on these things so is not an option in my view.

What say the experts?

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My advise is get a bigger outboard and run it at slow revs: at or below 3500 revs is the most economical speed for OB's.

Have a look at these high trust engines:FT60 / FT50 / FT25 / FT9.9 / FT8 2014 - Outboard Engines - Yamaha Motor UK

I would buy the 60hp model and run it at 3000 or 3500 revs which should use about 1gal/hr with the fine pitch prop.

Lovely relaxed cruising at slow revs.

>However, a motor run at half throttle will use less fuel? So, if I went with a 15hp, theoretically, would that be better? <

Mostly yes ,within reason on a gas engine , usually not on a diesel that gets efficiency thru being well loaded.

>I would buy the 60hp model and run it at 3000 or 3500 revs which should use about 1gal/hr with the fine pitch prop.<

With a modern gas outboard engine 1 gph is about 12-14 hp, I would look at the 25 at most with a large diameter prop , the boat would cruise quietly at 1/3 throttle.

CPseudonym said:

I'd say you can cruise them any way you wish. Whatever you wish to call them they look light, efficient and capable. Personally I think you can get by fine with less than 300 HP (assuming twin 150's) but it's all dependent upon what you want a boat to do. R Cooke at this forum has a boat quite similar to the one on the bottom picture and he regularly cruises long distances in it comfortably.

He has a book about it to you can find on Amazon I believe, Google his name.

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It's a 25' with diesel in/od so I'm wondering if it's comparable?

If you need 8hp, I'd probably go with a big displacement 15, or a 20. Take a look at how many CC's the engines displace. It is common for OB mfrs to use one engine block to make two or three hp ratings. Usually best to avoid the highest hp for the given engine block unless your are powering a go-fast.

I'm no fan of OB's on slow boats unless a diesel can't be fitted and made social. At low power settings, the gasoline engine efficiency drops way down, where the diesel maintains decent efficiency even down to say 15% load. Both engines burn less fuel at low throttle, but the diesel burns MUCH less. At say 75% load, the efficiency of each is not that super far apart.

OB's have one distinct advantage. Anything that goes wrong with it can be fixed with the "four bolt tuneup"!!!

The original name for a trawler was "Heavy Cruiser". The one thing that separates trawlers from most cruisers is weight. One could even say a cruiser becomes a trawler when it can't plane w an appropriate amount of power for that size of boat. But then hull shape would get into it. And I do believe there are trawlers that can plane. Perhaps not 30 knots but 15 or a large boat at 18. But whatever the hull shape or planing ability is I don't see how it can be a trawler unless it's heavier than a non-trawler pleasure boat. But the Albin 25 is definitely a trawler and only weighs 2 tons. But it's almost a FD hull, has diesel power and a keel that protects the prop. Is the Camano 31 a trawler? I'd say if you consider it's weight it may be .. just barely. And it is diesel. But there really is only one thing about the Canano that is unquestionably trawler and that's it's looks .. or styling. Dosn't even need fwd slanting pilothouse windows. Visually it's almost pure trawler.

To me a Sea Dory is definitely not a trawler but Sea Dory skippers do a lot of boating that is definitely trawler style boating. But that dosn't make their boats trawlers.

So I think weight is what makes a trawler. If your boat is heavy enough that using a heavy gear like a BW instead of light gear is not a consideration re performance, balance and overall weight you probably have a trawler. and what a trawler really is is a "Heavy Cruiser".

Presuming the prop is properly geared for the job:

Heres the fuel consumption for a 60hp 'under normal load':
http://www.suzukimarine.com/Product...C/Caravelle Powerboats/Caravelle 17 EBO DF60A

A high trust engine /fine prop under 'normal load' will use about the same: 1.4 gal at 3000 revs, even though your are FD vessel.

Rustybarge said:

Presuming the prop is properly geared for the job:

Heres the fuel consumption for a 60hp 'under normal load':
http://www.suzukimarine.com/Product...C/Caravelle Powerboats/Caravelle 17 EBO DF60A

A high trust engine /fine prop under 'normal load' will use about the same: 1.4 gal at 3000 revs, even though your are FD vessel.

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These data are hard to make much sense of as we don't know the hp being created. At 3000, boat is near the "hump", and the hp could be really anything.

At 4000, boat is planed out and using a 2.7exp prop curve, it comes out to 10hp per gph, which is pretty dismal. Probably better than that, but maybe not.

Rustybarge said:

Apologies to the forum: my posts are being moderated, so there is a delay before they appear.

3 or 4 of my posts have disappeared into the 'ether': I will wait to see if they reappear !

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Not anymore, new members with less than 10 posts have all posts with links embedded have to be checked for spam by a moderator first. I cleared the posts stuck in the que and you're good to go now. The posts appear before this quoted one on page 2 of this thread.

CPseudonym said:

Not anymore, new members with less than 10 posts have all posts with links embedded have to be checked for spam by a moderator first. I cleared the posts stuck in the que and you're good to go now. The posts appear before this quoted one on page 2 of this thread.

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Thanks.

Healhustler in post # 26 has depicted the better application as it relates to the thread.
To this it would be added practical actual experience of the hull speed aspect of OB application. Our former boat "Tenacious" weighed 19000# was SD configuration (Think 32 foot Grand Banks hull). We utilized a 9.9 "High Thrust" (Equal to a standard 15 HP OB) mounted on the swim step on a open market bracket. This drove the boat at 4.5 knots at 1/2 throttle. At full throttle this 9.9 was not pushing the boat at any more appreciable speed in terms of the high RPMs being used. At 1/2 throttle I'd had estimated that I would access a safe harbor with the OB fuel on hand or 6 plus hours of running.
On post #25 by Cappy, reflects the larger OBs in the upraise position on the same model boat.
Electric over Hydraulic lifts are standard on the larger OBs and optional on smaller (9.9) engines. The lower units can be raised out of the water to safeguard against corrosion conditions.

In the end, it is fully agreed that these large HP OBs are not comparable to our diesels large and small. Were there to be increased forum submissions on the subject perhaps the moderators would consider a specific category for the subject of OB driven trawlers.

Regards,
Al

Al said:

Healhustler in post # 26 has depicted the better application as it relates to the thread.
To this it would be added practical actual experience of the hull speed aspect of OB application. Our former boat "Tenacious" weighed 19000# was SD configuration (Think 32 foot Grand Banks hull). We utilized a 9.9 "High Thrust" (Equal to a standard 15 HP OB) mounted on the swim step on a open market bracket. This drove the boat at 4.5 knots at 1/2 throttle. At full throttle this 9.9 was not pushing the boat at any more appreciable speed in terms of the high RPMs being used. At 1/2 throttle I'd had estimated that I would access a safe harbor with the OB fuel on hand or 6 plus hours of running.
On post #25 by Cappy, reflects the larger OBs in the upraise position on the same model boat.
Electric over Hydraulic lifts are standard on the larger OBs and optional on smaller (9.9) engines. The lower units can be raised out of the water to safeguard against corrosion conditions.

In the end, it is fully agreed that these large HP OBs are not comparable to our diesels large and small. Were there to be increased forum submissions on the subject perhaps the moderators would consider a specific category for the subject of OB driven trawlers.

Regards,
Al

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In the UK and ireland the only boats with outboards are small planing boats up to about 20', and of course ribs which are very popular with the coast guard etc: these come in sizes up to about 30' with twin rigged engines.

But over the last couple of years manufactures are realising that the American tradition of big OB powered boats makes sense, like the Merry fisher 880 with 300 hp and the Antares 9 mtr.

Antares 8.80 / Antares Out-Board / Motorboats - BENETEAU



Ps: This is one of the very first mass produced large OB boats available on this side if the pond!!!
This is revolutionary here in Europe: a totally new direction for us.

Al said:

Were there to be increased forum submissions on the subject perhaps the moderators would consider a specific category for the subject of OB driven trawlers.

Regards,
Al

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We already have a section dedicated for that. Two in fact.