tilt or slide for outboard in a well

Discussion in 'Sailboats' started by CBTerry, Jun 11, 2017.

  1. CBTerry
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    CBTerry Junior Member

    Hello! I have a 30 foot Pearson Wanderer and a 15 horsepower Johnson sailmaster which I am trying to get together by building a well aft of the cockpit. It is an extra long shaft and I just received a 10 inch diameter four blade 5 inch pitch prop to push it about with. The decision I'm having trouble with is whether or not to have a vertical slide, which would require the building of a bit of a box on the aft deck for the motor to raised up into, or to have the motor tilt. Having the motor tilt would require slotting the transom as well as the bottom of the boat and the motor would be exposed and that could cause problems. The box I'm not too worried about building because I will probably be adding a mizzen mast to make her into a yawl. Getting the control cables to articulate the 30 inches or so might be problematic but I have a couple quite long cables so I think I can pull this off. I would love to hear opinions regarding the motor tilting or the motor traveling vertically (or anything else, such as dark matter, which I still think is a bit of a sketchy idea). Getting the motor to travel vertically I can easily have a bomb door for smooth, quiet sailing.
     
  2. Mr Efficiency
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    Mr Efficiency Senior Member

    Is the engine to have a steering function ? That will potentially affect the room required.
     
  3. CBTerry
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    CBTerry Junior Member

    I would like it to swing thru 90 or so degrees if possible. If I make the cut out large enough for the prop and the anti aeration plates to go through then there will be enough room for it to turn approximately that much or just a tad less. This is my measurements for the vertical slide arrangement. I am leaning heavily towards the vertical slide arrangement but wondering if I have forgotten one aspect or another or haven't thought of one characteristic or another. If I wanted to put davits off the back at some point to lift a dinghy out not having the foot of the outboard protruding aft would be a nice thing also
     
  4. Barry
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    Barry Senior Member

    [​IMG]There are lots of these types of lifts on the market, most often there is a spring that aids in lifting the weight of the motor. From here if you want you can tilt the motor for more clearance between the prop and the water. The bracket can be lowered to different heights.
     
  5. CBTerry
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    CBTerry Junior Member

    One of the reasons I am going too an outboard in a well instead of an inboard is for ease of docking and maneuverable thrust.
     
  6. PAR
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    PAR Yacht Designer/Builder

    There are good and bad things to consider with both approaches. With a slide, you'll need more height than commonly seen in a well box, but the cutout in the hull can be pretty small which is good for sailing. With a tilt up arrangement, you'll save some height on the box, but the hole will need to be long enough to let the lower leg swing up, which isn't good for sailing. I've also found slides tend to jam if any dirt, salt, etc. gets in them. The spring loaded transom mounts take a pretty big swing, but is a bit less than just the stock pivot mechanism.

    Rather than using a traditional steering setup, I used a simple link to my tiller to turn my outboard. It was little more than a piece of 3/8" rod, bent to go in a fitting on the rudderhead and the engine's tiller. It does have to be popped off, to tilt the engine up, but does permit vectored steering with the engine. My setup was offset to port permitting this simpler approuch.
     
  7. CBTerry
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    CBTerry Junior Member

    Thank you for your response. I had an outboard on one of those previously and the motor wood aerate the prop in short choppy Seas. It was only a long shaft and not an extra long shaft. By putting the motor in a well I will be moving it forward almost 2 feet. This will reduce the ark of the prop going up and down and so in Seas . hopefully it will not aerate as easily. Also being in the well the motor will be protected in heavier Seas and it will also look a lot better as well.
     
  8. CBTerry
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    CBTerry Junior Member

    Thank you for your reply. I am thinking of going with the slide arrangement for the benefits you've already mentioned. For some reason I am a bit fearful of having the foot of the motor stick out the back of the boat with a tilt-up Arrangement. It is an extra long shaft Johnson sailmaster. The Tilt app Arrangement would prohibit need from having a set of davits later if I so wish. Better sailing is important with the bomb door closed it will be nice and quiet. I like your idea of tying the tiller to the motor. Offsetting the motor is a good idea for me as well. I have been trying to come up with a fitting which the motor will engage when it slides down all the way that will be tied through solid Rod linkage to the tiller. It may wind up being a Rube Goldberg Affair though haha one of the reasons I am going to an outboard is so that I can have vectored thrust. I rarely motor sale and so primarily I motor off of a dock and so the outboard seems the better animal for me. Plus I have two of these motors complete and pieces parts to another one or two and I know a good bit about them and parts are plentiful. A short shaft for the dinghy and a long shaft for the Mothership. Same spares Etc if I ever do go extended cruising I can have a complete spare powerhead freshly rebuilt in a garbage bag tucked away somewhere. A complete rebuild is less than $500.
     
  9. Mr Efficiency
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    Mr Efficiency Senior Member

    How much elevation from the run position is required ? Can't be much more than a foot, unless you want it clear of the waterline, which would be somewhat more, presumably. You rather fancy a custom made vertical slide with Teflon or HDPE , and a coarse-threaded rod you could turn with a removeable hand crank, or even a pump-up air ram would give the narrowest slot.
     
  10. CBTerry
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    CBTerry Junior Member

    Yes I would like the prop clear of the water. Dragging stuff through the water bothers me psychologically haha part of the reason I am going with an outboard is because dragging a big problem a diesel through the water gives me nightmares. I will need to raise the motor approximately two and a half feet. I intend to use pulleys and a short bit of rope. I intend to have a bomb door that will close after retraction so that water doesn't slosh about in the well well sailing. The bomb door is just aft of the water line as the hull sweeps up out of the water. If I can attach the line such that it is pulling on the center of mass and parallel to the slides it should greatly reduce any problems of the slides catching. Standing on the ground the motor is 4ft tall and the power head is not very tall it is a Johnson 9.9 that is low profile.
     
  11. Mr Efficiency
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    Mr Efficiency Senior Member

    2.5 feet is a helluva lift, you can't get away with less ? I'd say you will have to make your own device.
     
  12. CBTerry
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    CBTerry Junior Member

    Oh yes I already understand that. I actually took the clamps, that typically hold the outboard motor to the transom, off of the motor and will bolt on two plates which have an 8 inch "T" to fit the top of the T into the track . The eighth inch measurement is vertical. In other words there will be two 8-inch long slides that will be captured in the tracks I build. The tracks will be 2 inches wide as the top of the T is a shade less than 2 inches. By sanding ( relieving) the leading edges of the T just so I should be able to prohibit a lot of sticking in the mechanism. also pulling parallel to the slides and at the center of mass, or just a little bit towards the track side of the Center of mass will alleviate sticking problems I hope.
     
  13. philSweet
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    philSweet Senior Member

    With all due respect, I think you are worrying about all the wrong things. Considering your location, I'm guessing you want to travel to the Bahamas and the Caribbean. It's a Wanderer, nice boat, but not something to worry about as far as a bit a prop drag goes. A two-bladed folding prop and diesel would be best. A fixed two-blader would be fine. It might add 6-8% to total drag, but this isn't bad. A simple OB in a well is a real challenge for cruising, especially when you have a bit of a counter stern to work with. You need to get the prop as deep as humanly possible - bottom of the cowl at the waterline. And you still need a 25" shaft. You say you have an "extra-long" shaft. I didn't know they made an extension kit for the 15hp Johnson. My old Cal used a 15hp Merc (25" extension kit) in a well and cruised the Bahamas for a couple decades with that configuration. It was a fixed mount, electric start, with remote throttle and shift. I pulled it once a year for maintenance.

    The real issues -

    1. Noise and exhaust fumes. The 5 pitch prop is a mistake. Hang a stock 9 1/4 x 10 or 9 3/8 x 9 and run just off idle. Fiddle with the carb and plugs to get it right at 1500 rpm or so. You only need 4 hp. The higher pitch prop lets you motorsail smoothly. The 5 pitch will run like a cog railroad, be horrifically loud, burn double the fuel, and produce twice the fumes. Add forced ventilation to the well, the motor can smother itself and you in a following breeze.

    2. Make sure you can still pull-start the motor. This may require some mods. I could release the steering lock and turn the motor to get a decent pull, but it was a pain.

    3. Get the prop deep. Do not do anything that sacrifices the depth you can sink the prop.

    4. This may sound obvious, but the well should be watertight with respect to the rest of the hull and drain out the hole. But I say this because many aren't and don't, and I once owned a boat where the OB just sat between the two aft berths in the aft cabin and the well sill was all of 4 inches above the waterline. This boat somehow survived the 2004 and 2005 hurricane seasons in the Keys. Even my Cal had a small weep hole from the well into the bilge to drain the area in front of the motor clamp.

    Photo of my old boat here: Blackrock 24 https://www.boatdesign.net/threads/blackrock-24.46525/page-3#post-660160

    My marina neighbor had a Cal/Jenson 30 with an 8hp two stroke that tilted up through a transom slot. It worked okay for him, and like yours, his boat had a bit of a counter stern that made the transom slot less of an offense. But the prop did collect lines and debris. Whether it actually saved any maintenance on the lower unit, I don't know. I suppose the prop stayed cleaner, but you're in Florida, how big a deal is it to clean the prop?

    For my money, fixed mount, deep as possible, and see if you can live with it. That's what my boat ended up with after twenty years. If you can't, go back to the diesel and a folding Martec. Forget about drag issues and bomb-bay doors. Steering would be nice, but it only works if the prop is in the water. Reverse backwashes the rudder and can throw the tiller over hard enough to break your leg.
     
    Last edited: Jun 28, 2017

  14. CBTerry
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    CBTerry Junior Member

    I motor sail very little. I use a motor only when absolutely necessary and I've had several boats with no motor at all on which I would sail off the anchor.
    Installing a diesel motor is not in the cards at all financially. If I was to install an inboard motor it would probably be an air-cooled gasoline engine using V belts to drive the prop shaft and I would have to have the prop shaft in bearings for thrust. Anyway that scenario is highly unlikely.
    The OB motor came with a 25 inch extension. All sailmaster Johnson Motors were configured this way. I had a 7 & a half horsepower 4-stroke with the stock prop and it would not get very high up into its RPM range that I could use maximum horsepower. I will see how the 5-inch 4 blade prop does. it is 10 inches in diameter. The motor exhausts through the propeller.
     
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