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Thread: Outboard Trawler?

  1. #1

    Default Outboard Trawler?

    I'd love a traditional looking trawler like those of Garden or Hanson or Tad Roberts, maybe 28-32' long, shallow-ish draft, cruising at 6-8 knots but capable of 12, lots of fuel capacity, that could be powered by a new, quiet, easily maintained outboard (or two), maybe in a well.
    How dumb is this?
    I don't want to revisit the old diesel vs. gas debates. But I'd love to hear your thoughts on the feasibility of a design like this. Is outboard power a stupid choice for a slow-moving heavy boat?

  2. #2
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    Default Re: Outboard Trawler?

    Why are you opposed to an inboard?

  3. #3
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    Default Re: Outboard Trawler?

    "How dumb is this?"

    Not dumb at all.

    "Is outboard power a stupid choice for a slow-moving heavy boat?"

    No, not at all. Just get the proper gear ratio and prop size.
    Hope for the best, but plan for the worst.

  4. #4
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    Default Re: Outboard Trawler?

    The proper gear ratio and prop size (both diameter and pitch) are the rub. It will save much headache if you can find an outfit that can sort through available lower end units for various brands of outboard and can match a prop to your boat's displacement and desired speed range with suitable reserve power for harsh days or if you take someone in tow. And it's a bit pricy. Ask various OB dealers but also poke around for prop shops and general marine engineer/mechanics.

  5. #5
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    Default Re: Outboard Trawler?

    Why not, look at the evolution of the big twin diesel sport fisherman, their being replaced by big, outboard powered, some over 50', center consoles, some with living accommodations and with outboards now up to 627 HP that could probably push a battleships around.

    http://www.seven-marine.com/motors/seven-627sv/

  6. #6
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    Default Re: Outboard Trawler?

    I think that there are outboard powered trawlers in production, though they may be higher speed boats. I also think I've seen something like it from Bolger and Friends.

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    Default Re: Outboard Trawler?

    Doug Hylan's Marsh Hen or, smaller, Bowler may be of interest.

    http://www.dhylanboats.com/new_construction/marsh_hen/

    Jeff

  8. #8
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    Default Re: Outboard Trawler?

    As Ian and I have mentioned, the gear ratio and prop size is critical for your pocketbook and enjoyment. As woodpile has noted, there are wonderfully powerful outboards on the market, but be aware that most are built with gearing & props that expect you to go fast. You need higher gear ratios and larger, lower-pitch props to put just enough power into the water to move you at the desired speed without lugging the engine or cavitating the prop, or both.
    Hope for the best, but plan for the worst.

  9. #9
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    Default Re: Outboard Trawler?

    I see that Yamaha now has a "high thrust" selection of HP - 60, 50, 25, 9.9 - all big gear ratios and many props. The site looks pretty user friendly though you'll still want to go over it all with a good engineer.

  10. #10
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    Default Re: Outboard Trawler?

    Ian, Yamaha has had most of these for many years. We bought our T50 hp High Thrust in 2005, and have done about 1000 miles each summer since, at slow cruising speed in our 24 foot pocket trawler. If I was building the boat today, I would probably specify twin T25s, instead of one T50 and a T9.9 as a get-you-home backup.

    They are all good, well proven units.

    Tony.

  11. #11

    Default Re: Outboard Trawler?

    Thank you all very much. I wish someone a lot smarter than I am would design and spec such a hull and motor setup. I believe there would be an enthusiastic market.

  12. #12
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    Default Re: Outboard Trawler?

    There are interesting problems with twin engines rather than one. Meg is of a size where she really needs 40 hp but she is too shallow to b=fit a single prop big enough to get 40 hp into the water. So, 2 @ 20 hp. This is considerably more expensive at just the engines, not to mention the gear boxes and props.

    The other problem is reliability. Here airplane experience is more detailed. Given a general capacity, twins turn out to have more engine failure related crashes than single engine planes. It may be as simple as if you only have one, you pay more attentionl

    Food for thought.

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    Default Re: Outboard Trawler?

    Mainman, that sounds like an interesting project. I may be facing a slow time in the next month or two, so maybe a spec project is in order. What style of construction should it be - ply-on-frame, stitch-and-tape ply, strip-cold-molded (my favourite), traditional plank-on-frame?

    Anybody else interested, at least to the point of spending $25 on study plans?
    Hope for the best, but plan for the worst.

  14. #14
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    Default Re: Outboard Trawler?

    Quote Originally Posted by Ian McColgin View Post
    There are interesting problems with twin engines rather than one. Meg is of a size where she really needs 40 hp but she is too shallow to b=fit a single prop big enough to get 40 hp into the water. So, 2 @ 20 hp. This is considerably more expensive at just the engines, not to mention the gear boxes and props.

    The other problem is reliability. Here airplane experience is more detailed. Given a general capacity, twins turn out to have more engine failure related crashes than single engine planes. It may be as simple as if you only have one, you pay more attentionl

    Food for thought.
    I used to look after a few air taxis, light twin engined a/craft. The Twin Commanche, for example, had a bit of a reputation for stall/spin crashes after an engine failure. But, since they were cheap to operate, they were often used for training with simulated engine failures. At that time, I recall that training for engine failures resulted in more crashes than actuall engine failures...
    Also, quite a few twins had trouble maintaining height on one, if well loaded or in hot condirions. So the remaining engine just moved the site a bit further on.
    On a boat, you just go a bit slower and lean on the wheel. In the air, you need to do several things reasonably quickly, especially if at low speed.
    A2

    In terms of reliability, it was worked out that three engines was best on the cost/safety basis.

    Back to outboard trawlers...
    Last edited by Andrew2; 12-25-2018 at 03:29 AM.

  15. #15
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    Default Re: Outboard Trawler?

    Quote Originally Posted by mmd View Post
    Mainman, that sounds like an interesting project. I may be facing a slow time in the next month or two, so maybe a spec project is in order. What style of construction should it be - ply-on-frame, stitch-and-tape ply, strip-cold-molded (my favourite), traditional plank-on-frame?

    Anybody else interested, at least to the point of spending $25 on study plans?
    MMD, that's an interesting way to spend a few Xmas days. To start things off, a reference to a previous generation's ideas may be interesting to some. John Atkin's Martha Green 24 footer was a ballasted boat (1500 of lead pigs, stowed in the bilges), with a low power inboard (Google it). I looked at Atkin's concepts when I was thinking out my own approach to a comfortable small cruiser over 15 years ago now. The Builder's remarks on pages 59 ff of Atkin's "Practical Small Boat Designs" about slow speed cruising, and comfort generally certainly influenced me, and his thoughts were reinforced by reading Dave Gerr's ideas on comfort and "heave" in Chapter 14 of The Nature of Boats.

    The result is pictured below (in the next post, to avoid screwing up this one), and has served us well over the years. Essentially, it's a small lobster boat, with the run modified a bit (it's not as flat as is customary), and 750 pounds of internal bonded ballast. With that plus fuel, water, two large batteries and stores, it weighs some 5000 pounds, and while the house is a bit boxy (a typical amateur mistake), it is still a good seaboat (as we confirmed when caught out in the Bay of Fundy a few years ago). After this time, we (of course) have two foot-itis, and if building again today, would probably extend the stern a few feet, still leaving the house roughly a-midships.

    Regards, Tony.
    Last edited by Tonyr; 12-25-2018 at 09:00 AM. Reason: Jane changed to Green - thanks, Ian.

  16. #16
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    Default Re: Outboard Trawler?

    I think Tonyr means John Atkins' Martha Green. I don't see her as an outboard but she is a charming boat. I'd raise the cockpit sole.


  17. #17
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    Default Re: Outboard Trawler?

    IMG_0697.jpg Us from about 2013

    Tony.

  18. #18
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    Default Re: Outboard Trawler?

    Ian, Yes, that's the one. Too much Xmas breakfast. Of course, not an outboard, but influential in that it helped to persuade me that a "small" vessel could also be a comfortable one for a pair of old fogies in their (boating ) dotage.

    Tony.

  19. #19

    Default Re: Outboard Trawler?

    This is exciting. I don't always understand the naval architecture details being discussed, but I admire your knowledge very much.
    There must be an existing trawler-style design that could be made to work efficiently with outboards. So many older downeast hulls here in Maine get their keels shaved down and converted to outboard power. Some owners report being happy with the results. But some don't.

    Sign me up, mmd. I'd prefer a strip-built hull but imagine that stitch-and glue ply would be less expensive.

    Not that it matters, but this is what I've been dreaming about:
    28-32' long, beam doesn't need to be less than 8'6", draft under 3'
    Traditional sedan style to maximize interior living space, rather than a raised pilot house
    Hard chines to make time at anchor more comfortable.
    Outboard(s) in a wells(s) or on a bracket
    Maybe 5' of cockpit space for fishing and pulling a trap or two
    Simple, right?

  20. #20
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    Default Re: Outboard Trawler?


  21. #21
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    Default Re: Outboard Trawler?

    Why the heck not!

    There's lots of high thrust outboards out there in the 200-250 hp range, and they could be installed in an acoustic box to make them very quiet. Think of all that hull space that would be freed up by using them instead of inboards, and modern, 4 strokes are both reliable and fuel efficient.

    Sounds like a fine idea.

    Jeff

  22. #22
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    Default Re: Outboard Trawler?

    I don't like big outboard motors......... except for on certain types of high speed boats.

    My reasons are two:

    1. Durability. You could buy a 50 years old Perkins diesel out of a scrapped combine harvester and rebuild it and convert it for marine use with freshwater cooling and run it for 50 years more..... and then rebuild it once again. Heavy diesels can be kept running for generations as long as there are spare parts on the market but as the motors are longlasting there are usually at least some spare parts. Outboard motors are built as consumables to be thrown away once they have a decade of use or maybe two on them.

    2. Safety. Outboard motors have a completely unprotected propeller hanging from a brittle cast aluminium gearbox. The first time you touch a rock or even a smooth gravel bank all shose parts will be shattered and the boat without propulsion. On the other hand it is possible to buld some rather efficient protection around the a propeller mounted on a straigh shaft through a keel that protrudes below the propeller. That's why I don't like outboards on boats that you cannot row efficiently.

    There are just my thoughts......
    Amateur living on the western coast of Finland

  23. #23
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    Default Re: Outboard Trawler?

    Quote Originally Posted by rbgarr View Post
    Provided that she was really a smaller version - TUVA is a really BIG boat by my standards (but I do like its "lobster boat" type hull).

    Among the (many) design trade-offs we should consider, are the one of hull form Vs quietness at anchor. I have noticed that chines tend to be noisy when you are trying to get to sleep - too much slap slap for my taste. One can design round this issue, but why bother if you don't have to when form stability at speed is not an issue (since we are not going fast, its a slow speed trawler, right)? Choices, choices.................

    Tony.

  24. #24
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    Default Re: Outboard Trawler?

    Tad Roberts has his Wedge Point series. The 27 is designed to run up to 10 knots on a 25 hp high-thrust Yamaha. The 31 requires a 90 hp motor. I'm certain I've seen other outboard powered cruising designs, not to mention Bolger's many offerings. Great project, please keep us posted.
    -Dave

  25. #25
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    Default Re: Outboard Trawler?

    MMD's offer is an interesting one! A quick sketch of his notions would be interesting to compare to Tad Roberts response on his Facebook page here: https://www.facebook.com/profile.php...AdModw&fref=nf

    We have a 24' Gartside vee-bottom inboard cruiser that might fall into the category of 'trawler' type and have no issues with the chines slapping at anchor. Occasionally we'll get a 'bump' in a beam sea but the advantages of a simpler build than round bottom are worth considering. See some of his similar designs here, some of which he could work over for outboard powered options: https://store.gartsideboats.com/coll...r-boats?page=3

  26. #26
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    Default Re: Outboard Trawler?

    Have a look at the website for the Rosborough RF-246.

  27. #27
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    Default Re: Outboard Trawler?

    Devlin has a few versions of mini-tugalike with outboards. Just change the above-deck style a little, they aren't really tugs below the waterline anyhow. Several in here that fit your description :

    https://www.devlinboat.com/wordpress...able-as-plans/

    Or did you have your heart set on dragging around three tons of fish ?

  28. #28
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    Default Re: Outboard Trawler?

    F9A5351D-3E3A-4DD5-95C9-09AE5364DE3B.jpg
    Uses a high-thrust Honda 60hp.

  29. #29
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    Default Re: Outboard Trawler?

    Look at a design called Blue Jacket. I used a Yamaha 9.9 High Thrust on my 28' Shearwater Yawl for 18 years and was enormously pleased with it. Yamaha HT motors are a very different animal from other OB's; larger dia, slower turning props; great for slower-moving hulls.

    Quote Originally Posted by maineman View Post
    Thank you all very much. I wish someone a lot smarter than I am would design and spec such a hull and motor setup. I believe there would be an enthusiastic market.

  30. #30
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    Default Re: Outboard Trawler?

    #28 is a Bluejacket 25.5

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