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Thread: Dory Motor Wells

  1. #1
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    Default Dory Motor Wells

    Hello everyone, this is my first post that involves a question about the design and installation of a motor well in a Grand Banks style dory. I'm a genuine dory fan and owned a 20' Lowell sportsman (should have never sold that boat ) before my current 18' banker. The Lowell had a motor well that included a slot in the counter that allowed full tilt of the outboard for beaching. However, it eliminated a lot of displacement at the stern.

    My current dory, constructed with care by a fine older gentleman in Newfoundland does not have a motor well, but the transom was made wide enough to accomodate an outboard. I bought a 9.9 HP Honda with an extra long sailboat shaft (28") and fabricated an aluminum bracket to mount the motor vertical. Unfortunately, this seems to be an unsatisfactory arrangement. The boat squats terribly to the stern and a tiller extension would have to be about six feet long to properly balance the dory!

    This brings me back to the subject of motor wells. Had I known better, I would have had one built in from the start. I've got John Gardner's Dory book and it does briefly cover some issues, but not for my application. I would be very interested in the thoughts of boat enthusiests on this forum.

    1. How can one design a motor well that allows tilting with MINIMAL displacement loss?

    2. Is tilting required at all? I've got a couple other outboards right now that are light enough to easily be lifted when required. One is a 2 HP honda four stroke 15 " shaft and the other is a 5 hp Nissan four stroke with a 20" shaft. As everyone here knows, horsepower isn't really an issue with this style hull design so perhaps a smaller motor would be better if the smallest size motor well is the goal. The question is with a minimal motor well, what happens if you hit an underwater obstruction? (I'm not really worried about damaging a motor, but I don't want to find myself sinking in 36 degree Michgan water in November )

    On the other hand, a two cylinder outboard is MUCH smoother compared to one cylinder "thumpers." So, if I'm going to accomodate the sewing machine smooth, but much heavier Honda 9.9, there will have to be some sort of a tilt arrangement. Any ideas?
    Last edited by Rick-Mi; 04-13-2006 at 08:42 AM.

  2. #2
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    This is probably not much help but if you're not comfortable designing your own well there are boat plans out there that detail them such as this St Pierre dory from Glen-L. Problem is you'd have to buy the plans for the boat in order to get the details for the well.



  3. #3
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    I know of one banks dory fitted with a motor well that is a rather elegant solution to the problem. The well is fitted about four feet abaft of 'midships and rigged with a vertically-sliding bracket that is operated by a multiple-purchase block-and-tackle. The motor is fixed in place and neither tilts nor swivels (steers). The dory is fitted with a transom-mounted rudder and tiller, and the motor merely provides propulsive power, not steering (the boat also is sail-rigged). When the motor needs to be withdrawn, hauling on the tackle hoists it vertically into its small well. The issue with this type of installation is providing adequate ventilation for combustion airsupply , and heat & exhaust fume dissapation.
    Hope for the best, but plan for the worst.

  4. #4
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    I used a banks style dory with a motor well to get to and from an island on the coast of Maine where I was working on, taking care of, and living in a house. It was basically a bulkhead across the aft end of the boat, maybe 6" forward of the bottom end of the transom. Tilting was accomodated by cutting away a good bit of the lower part of the transom as well as a bit of the garboard strake if I remember correctly (it has been about 12 years since I've seen that boat). The motor was an old, heavy outboard that stayed on the boat all the time, and the boat often stayed in the water pretty much whenever the water was not hard (as in frozen) so full tilting was essential.

    An extension was necessary to get my weight a bit forward in the boat, but it was a much more reasonable extension than would be required if the motor had been out on the transom. On this boat at least, it would have been a challange to even get to the motor to start it if it had been hanging off the transom, at least without a passenger or some cargo up forward to balance out my weight and the weight of the motor.

    This approach does make a bit of a mess of the transom and garboard strake, making it harder to covert the boat back to a non-motor well boat than a free-standing well would, but it also leaves more space for cargo and passengers.

    As I'm sure you know, banks style dories are always going to squat in a hurry if you try to push them with a motor. They just do not have enough width aft to work well at any sort of speed.

  5. #5
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    Thank you so much for the prompt responses! I've lurked occasionally on this forum for a long time. What a great buch of people......

    Jim, I'm familiar with the St Pierre style dories. Unfortunatley, while the lever controlled motor well floor is a great idea to prevent motor suction problems, they are rather large. My 18 foot dory is a pretty small boat.

  6. #6
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    Quote Originally Posted by mmd
    I know of one banks dory fitted with a motor well that is a rather elegant solution to the problem. The well is fitted about four feet abaft of 'midships and rigged with a vertically-sliding bracket that is operated by a multiple-purchase block-and-tackle. The motor is fixed in place and neither tilts nor swivels (steers). The dory is fitted with a transom-mounted rudder and tiller, and the motor merely provides propulsive power, not steering (the boat also is sail-rigged). When the motor needs to be withdrawn, hauling on the tackle hoists it vertically into its small well. The issue with this type of installation is providing adequate ventilation for combustion airsupply , and heat & exhaust fume dissapation.

    That seems to be a VERY workable idea mmd! I've read before that a rudder is vastly superior for handling in rough seas. But, how bad do you think an outboard would perform if located slightly aft of midships for ideal weight distribuiton without a rudder? Seems to me it would be better than oars could muster and I've spent plenty of time rowing on the open water. On the other hand, perhaps not. With a 2 or 5 HP motor, a simple sliding backet to manually lift would work fine. Air supply doesn't seem to be a problem here, but dealing with a water stream might. In this case it seems the air cooled 2 HP would get the nod. Still, that 9.9 two cylinder is a really superior outboard and would be nice to accomodate.
    Last edited by Rick-Mi; 04-12-2006 at 01:02 PM.

  7. #7
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    I've always wished I could re-engineer the most elegant dory motor well I ever saw - the boat now long gone.

    The fore and aft dimensions of the well box were a bit longer than the motor at the top. The aft wall sloped from the back of the open top back and down to go through the bottom at the place where the motor was tilted up forty five degrees. The motor was mounted on a plate that was attached by two arms on each side that could ride on sliders, such that once the motor was tilted to 45 degrees, it could then, mount and all, slide up. A very easy slide.

    A piece of brilliant home engineering by my friend's grandfather but an uncle made off with the boat before I could draw the well mechanism.

    G'luck

  8. #8
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    Quote Originally Posted by Bruce Hooke
    I used a banks style dory with a motor well to get to and from an island on the coast of Maine where I was working on, taking care of, and living in a house. It was basically a bulkhead across the aft end of the boat, maybe 6" forward of the bottom end of the transom. Tilting was accomodated by cutting away a good bit of the lower part of the transom as well as a bit of the garboard strake if I remember correctly (it has been about 12 years since I've seen that boat). The motor was an old, heavy outboard that stayed on the boat all the time, and the boat often stayed in the water pretty much whenever the water was not hard (as in frozen) so full tilting was essential.

    An extension was necessary to get my weight a bit forward in the boat, but it was a much more reasonable extension than would be required if the motor had been out on the transom. On this boat at least, it would have been a challange to even get to the motor to start it if it had been hanging off the transom, at least without a passenger or some cargo up forward to balance out my weight and the weight of the motor.

    This approach does make a bit of a mess of the transom and garboard strake, making it harder to covert the boat back to a non-motor well boat than a free-standing well would, but it also leaves more space for cargo and passengers.

    As I'm sure you know, banks style dories are always going to squat in a hurry if you try to push them with a motor. They just do not have enough width aft to work well at any sort of speed.

    Bruce, of course your right about trying to push dories with an outboard. They knife thourgh the water with magical grace up to a point and then they quickly hit the wall! No point even trying to power them up. Heck, there is no need to. I've traveled great distances in a very satisfactory manner with that 20 foot Lowell and a 5 HP four stroke Nissan. But, I much prefer a two cylinder motor for smoothness if I have a choice.

    The motor well syle you describe sounds very much like the Lowell design. Had I known, the boat could have been built that way from the beginning At this point, as you mention it would take some MAJOR modifications to do that. Honestly, an extensive project like that might be beyond my abilities at this point and time and it would be easy to mangle a very nice boat. Luckily, transom is plenty wide enough (12") at the very bottom to accomodate a tunnel without hacking up the garboard strake. That certainly is an option.

  9. #9
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    Quote Originally Posted by Ian McColgin
    I've always wished I could re-engineer the most elegant dory motor well I ever saw - the boat now long gone.

    The fore and aft dimensions of the well box were a bit longer than the motor at the top. The aft wall sloped from the back of the open top back and down to go through the bottom at the place where the motor was tilted up forty five degrees. The motor was mounted on a plate that was attached by two arms on each side that could ride on sliders, such that once the motor was tilted to 45 degrees, it could then, mount and all, slide up. A very easy slide.

    A piece of brilliant home engineering by my friend's grandfather but an uncle made off with the boat before I could draw the well mechanism.

    G'luck

    Ian, that sounds like an extremely well thought out design!!! Wouldn't it be great to have some pics and drawings of that set up......
    Last edited by Rick-Mi; 04-12-2006 at 01:04 PM.

  10. #10
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    I have to say that I sure do like outboard stearing for close manouvering. There is nothing quite like being able to rotate the motor 90 degrees to one side or the other and pretty much spin in place when you are trying to squirm through a tight spot or make your way around a crowded waterfront. That said, for going longer distances, being freed from the motor and able to stear with, say, a lever up closer to amidships would be mighty fine.

  11. #11
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    Quote Originally Posted by Bruce Hooke
    I have to say that I sure do like outboard stearing for close manouvering. There is nothing quite like being able to rotate the motor 90 degrees to one side or the other and pretty much spin in place when you are trying to squirm through a tight spot or make your way around a crowded waterfront. That said, for going longer distances, being freed from the motor and able to stear with, say, a lever up closer to amidships would be mighty fine.

    Yes, and that is what makes a loooooooong tiller extension so poor in this current set up. By the time you make it long enough to operate the outboard from amidships it's unworkable for any type of responsive control.

    Your comments about the convenience of sterring with a lever amidships brings up another possibility that I've been kicking around to solve the problem. I do have a stick steer mechanism that is the perfect length to control the motor slightly forward of center for IDEAL weight distribution. As you probably know, stick steering is very popular with serious crappie and bass fishermen who want responsive control from the front of the boat. The only problem with this is my brand new, out of the crate Honda outboard isn't set up for remote! Unfortunately, the normally brilliant engineers at Honda made this series an either/or proposition between tiller and remote. So if I go that route it requires the expense and aggravation of buying and selling motors simply to duplicate what I already have.

  12. #12
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    Another thing to consider with outboard motor wells is the noise and smells -- hey, I be a poet!

    Seriously, I've read several accounts of people building wells, using them for a short time, and then moving the noisy beast back to the transom. For an 18-ft open Bank dory, I suspect that anything over that 2hp Honda would not only be overkill powerwise, but might also create a bit of a pong, as the Brits so quaintly put it.

    See if you can wrangle a ride in a similar-sized open boat with a well. I know that you don't have many other options, just don't want you to find out too late that the noise and/or fumes mean you regret cutting that large hole in the bottom planks.

    Whatever you decide, best of luck with your 'new' dory!
    "The enemies of reason have a certain blind look."
    Doctor Jacquin to Lieutenant D'Hubert, in Ridley Scott's first major film _The Duellists_.

  13. #13
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    Howdy, Rick.

    I've got a simple well on my 17' Swampscott dory, basically just a box with a minimum size hole for the prop to get through. I attached a rubber boot (gasket material) to the underside of the well to minimize any splashing. I think the boot also helps keep exhaust from drifting back up through the well. With a 5 hp Nissan 4-stroke, short shaft, I've had no complaints. Noise, vibration, smoke... not much of an issue, in my opinion. I've heard it often repeated that a single cylinder motor vibrates more than a twin, but I don't think there is a noticable difference with todays very fine little 4-strokes. They're pretty smooth and quiet.

    I'm sure a 2 hp will be enough for your dory, but 4 to 6 wouldn't really be wasted. I reach hull speed at about quarter throttle, but I frequently run at half throttle or more when working against a current. I'm in a bit of a trough when doing so, of course, but that is the nature of the beast. At full throttle, water starts coming in through the sculling notch in the transom... so I don't run at full throttle.

    I don't find it hard to balance the weights in the boat, even though the tiller is somewhat aft of center. I usually have at least one passenger, and if not, I just move as much gear as possible up into the bow. I don't even bother with a tiller extension, even though I have one.

    If I were doing it again, I would do it exactly the same way. No way would I bother with a tilt up well. The vertical lifting mechanism sounds clever; maybe I would try my hand at that. But I generally subscribe to the K.I.S.S. principle. And I've had no problem beaching my dory, even without lifting the motor out of the well. I just look for the steepest section of bank, nose up there, and let the lower end of the motor sit in the mud. This wouldn't work so well if you boat in really rocky areas; around here it just isn't an issue.

  14. #14
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    LW, thanks for the suggestions. I'll bet you really like your swampscott dory. I understand they row like a dream and the slightly rounded sides really flow well with chop and swells on open water. Gig Harbor Boats makes a fiberglass version that looks extremely appealing. I suppose it's probably only a matter of time until I run across one and snap it up.

    It's a small world because like I stated earlier, I powered my previous 20 ft. Lowell Dory with a 5 HP Nissan, four stroke. They are outstanding little motors that sip gas and are reasonably smooth. But, if you ever stuck a small twin Honda or Yamaha four stroke on there you would be absolutely amazed at the difference in vibration.
    Last edited by Rick-Mi; 04-12-2006 at 05:40 PM.

  15. #15
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    Yeah Rick, it is a great all around boat.

    I built mine with a centerboard and yoke steering, with the leg of mutton sail from The Dory Book. It sails and rows well, but I've mostly used it for fishing under power.

  16. #16
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    I just bought a Yamaha 8hp TWIN CYLINDER remote w/builtin tilt 4 stroke. (20 or 25" shaft available) Selling the Honda and switching to the Yammy could solve part of the problem.

    Or try going electric , but add a Honda super-quiet generator in the bow to keep the batteries charged while cruising, and put a large minn_kota on the rudder.

    Just my thoughts, Good luck...

    edit : Plus you can use the Honda Generator around the house when the lights go out, something the outboard can't do for you.

  17. #17
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    Openboater,

    An electric dory, what a great idea! I've run a search on this topic and see many people are powering with an electric trolling motor built into the rudder. One thing is for sure, you can strategically place the battery(s) for ideal weight distribution. From a quick read it appears battery life with a 54lb motor is about 3 1/2 hours. With dual batteries and a 5MPH speed that is a considerable range without any on board recharging system to make noise and exhaust fumes. I have no idea how a system such as that would perform into a stiff wind with high seas. But, electric power is certainly an interesting idea with some considerable appeal.....

  18. #18

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    I owned a 17' swampscot dory that came with a tempermental 7.5 horse outboard ,this would push it beyond hull speed it seams as it would just push a wall of water .
    I purchased a salt water series trolling motor (54lb I believe) from west marine and used a trolling motor battery .We really liked this setup ,the power and the silence were very good and it did just fine against moderate current and wind .We usually had a cooler ,myself, wife and 10 year old daughter in the boat.

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