Engine well for CS17

[Scott Dufour]

I built my CS17 with the aft deck.  I like it.  But now I think I want to add a small motor (sorry Ray).  I think this question will need Graham's input.

I'd like to convert some of that aft storage space to a motor well for a lil' tilt-up job. 

First:  Is it structurally feasible?

Second:  Is it structurally advisable?

Third:  Dimensions, framing requirements, drag minimizing modifications...?

Fourth:  All the other stuff I should think about...

[Ray Frechette Jr]

As much as I could never envision adding a motor to a CS series boat I would build for my own use,  every single one coming out of the shop has a structural reinforcement to transom to allow future owners to add an outboard bracket.

Is there some reason you want an internal well as opposed to mounting on a bracket??

Graham is busy teaching Fundamentals of Yacht Design at Wooden Boat this week and then has to drive home, so it may be a week or two before he chimes in here.

If you check out pics on this page;

http://www.jwboatdesigns.co.nz/plans/pathfinder/photo_album.htm

you will see how John Welsford designs in a well similar to what you describe on his Pathfinder design.

To my mind the cost benefit ratio on a re fab would lean me heavily to placing a bracket on the back if I lost confidence in my ability to navigate with sail and oars.    No disrespect intended there,  just I really don't discern any benefit to a motor myself on these boats.  I allow how others have different views on the matter though.

[wkisting]

Scott,

I have a motor on our CS20. At the time of the build, I considered a well, but rejected the idea after taking measurements on my boat. Even with a short-shaft motor (which is what we use), the freeboard/deck-height on the CS is low enough that the top of the motor would almost certainly sit higher than the deck (assuming you will mount it "properly" so that when tilted forward, it is actually out of the water). If, on the other hand, you accept that it will drag a bit even when tilted and thus decide to mount it lower, then you might be able to build a well and mount low enough to keep the engine cowl below deck level, but I also suspect you might get some head submergence in a heavy sea. To my mind, both options were unacceptable since they compromise aesthetics and performance.

We opted to make a custom-built motor bracket hanging off the transom and it works well. The downside, of course, is that you need to lean over the aft deck to operate the motor controls (except the tiller level, which sticks forward far enough to be fairly handy from the cockpit) and it can be a bit tricky to refill the motor-mounted gas tank if the waves are choppy, while you balance on the aft deck with a small gas can in hand. On the plus side, we mounted out motor at a nice height and have never had the prop come out of the water yet (though we haven't had her in seas over 3' high, either).

A motor well wouldn't afford many advantages even if it could be made to work, but it could potentially reduce sailing performance (the cut out slot in the hull might change planing performance) and I think it would be very tricky to build on a finished boat with the deck already attached. Given how well our bracket mount has worked, I would really recommend giving more consideration to that option. There are some commercially available mounting brackets that wouold be very easy to fit to a CS17 transom, and you would only n eed to add a little interior beefing up support.

[Richard Whitney CS#70]

Hi Scott

I built in a recess for the Yamaha 4hp 4stroke I was using (think it might have been a longshaft - cant remember)

Attached is a photo.  I just built it in 'by eye' and it worked well for me. 

[Scott Dufour]

Ah... ok.  Thanks Ray, Richand and Wes.

I was hoping to hide the motor below the deck, keeping that nice clean look and preventing mizzen line fouling, but Wes killed that idea with actual measurements and facts and stuff.  And with that long aft deck and significant coaming, the long lean-over-to-fill-the-tank-and-start doesn't sound appealing.

Richard's recess area is interesting:  did you mount it over the edge of the transom (so cowling in inside forward of the transome when tilted up)?

Ray- I sail out of Niantic harbour, and have to navigate a narrow and twisty channel under two bridges with currents in the 2-3 knot range.  The oars just aren't working for me...  lazy.

[Hirilonde]

I sail out of Niantic harbour, and have to navigate a narrow and twisty channel under two bridges with currents in the 2-3 knot range.  The oars just aren't working for me...  lazy.

I bought my Renegade from a man in Niantic.  I had to sail her home that route.  I would really lean towards having a no outboard Core Sound under just about any circumstances except yours.  Good luck choosing the best way to mount one.  As much as hiding it would be aesthetically pleasing, a mount or recess is probably much more practical.

[Scott Dufour]

See, Ray.  Dave says I'm not a wussy!

Am I right in assuming the recess brings the motor closer?  Could I run the fuel line up along the underside of the deck and through an opening (gasketed) at the top of the recess?  Any tricks to make the motor less prone to snagging the mizzen sheet?

[PAR]

A single ended tackle on a bridle will work better for snags.

An engine well will bring the outboard about 9" closer to the boat, compared to typical transom brackets.

[Ray Frechette Jr]

Ray- I sail out of Niantic harbour, and have to navigate a narrow and twisty channel under two bridges with currents in the 2-3 knot range.  The oars just aren't working for me...  lazy.

OK if I had to face that  regularly I migth reconsider the motor thing.

But before doing that I would consider other launch points....

And if I opted for the motor route I would still go with a bracket myself.  Is negotiating this channel the only time you need a motor?

If so the amount of time hanging ovcer the back would be minimized anyway..

But ahh the problems we face when we surrender to the siren call of infernal combustion devices.

So many times you will be tempted to start it up since it is there....

[Ken_Potts]

  Yes, like when trying to get under a bridge and out of the way of traffic against the current.  That's not a hypothetical one, it happened last time I was on salt water.  Come to think of it, earlier that day we were headed down the ICW with no wind at all.  When the wind died, we fired up the motor - When the wind started, the motor fell mercifully silent again.  It sure was nice to power the boat with gas instead of sweat in the 95 degree heat.    We had miles to cover before camping that day and the motor allowed us to get to the beach just at sunset.

  Having the motor on the transom allows me to go places that I wouldn't go otherwise.

[wkisting]

Ken is right, the heat is exactly what made equipping a motor on our CS20 an easy decision. This Georgia heat is unrelenting, and even though we built a fine pair of oars, the last thing you want to do in the summer is row. The motor really gives us a lot more options, and has been a nice luxury when we take friends out who have small children... when the wind dies, the kids get bored quickly, so we fire up the motor, run them over to an island to set them free to explore, and everyone is happy--much better than baking in the merciless sun with no breeze. 

Scott, the engine recess idea would definitely bring the motor closer, if that's a concern. Our bracket-mounted motor hangs about 13" aft of the transom, but the motor's tiller arm/throttle is quite easy to reach and adjust from the cockpit. We do have to lean over the aft deck a bit to pull-start the motor and a bit more to shift between N and F, but the only serious leaning involved is when you need to access the gas tank or turn on/off the gas flow valve. You get used to it pretty quickly, though. I only find the motor location obnoxious when trying to maneuver alone to a dock or hard landing. Then it can be a bit nerve-wracking to try to adjust the throttle, turn the motor and the sailboat tiller (turning both gives a much tighter turning radius than just turning one or the other), and still continue looking ahead to monitor progress so I don't collide with the dock or land roughly on a cement ramp. With a second person aboard keeping watch at the bow, the whole affair is much easier, so it is really only solo motoring in tight conditions makes the mount feel inconvenient.

One easy way to fix much of the hassle, would be to install a hard link between the sailboat tiller and the motor, so that they turn together... that's on my project list for the near future because then I could just reduce throttle to a gentle idle and ease the boat in to the shore while steering from the cockpit using the sailboat tiller (not leaning aft or sitting on the aft deck). I don't know whether having the motor several inches closer using the recess in the aft deck would add much convenience, and I personally chose to avoid it because I didn't want to cut into the deck.

[Scott Dufour]

Good feedback, Wes. Thank you.  If you linked the rudder to the motor, would you still be able to tilt up the motor?

Richard, how do you feel the recess performed vs hanging the motor on a mount.  Was it worth the effort?

[tom151]

Here's a simple technique for turning the engine with the rudder that does not require fixed struts.

The the line from the rudder (or rudder case) to the motor pulls the motor in that direction and the bungee pulls it back to the opposite lock.

To me it looks like you rig it so that the engine can be lifted without unhooking anything - just letting the bungee stretch if need be.

I'd choose different attachment points for the line and the bungee, but that would vary from boat to boat.

Pic attached

[wkisting]

Scott, I was going to suggest soft links but TomH beat me to it! I think with rope links like that, you could tilt the motor up without disconnecting anything. However, I'm going to play around with a few different ideas to see what setup works best. The benefit of a hard link is that you only need one connecting arm and it could probably be easily removable for tilting the motor up... if I cobble something together for a prototype, I'll post a pic, but that's probably a way off in the future yet.

[Scott Dufour]

Ok, then. Thanks for all the help.  Here's what I think my plan will be:

1) Pick up a used outboard -something like a Tohatsu  4,5,or 6 hp 4-stroke.

2) Pick up an outboard bracket, maybe a Garelick with the springs and vertical lift.

Try 'em out.  If I want the engine closer, I can always put a recess in at a later time.

So questions about the engine and bracket, because I really know NOTHING about these things.

a) Engine shaft:  15" (short) or 20" (long)?

Bracket vertical lift range:  they seem to come in ranges from 0 to, like 15 inches.  What do I really need?

Perhaps the answer to "b" is contingent on "a"?  If so, what's the recommendation?

[Gordy Hill]

Scott,

The guys with the West Coast Sailing Squadron use Honda 2 of 2.5 hp four strokes on their SeaPearls and swear by them. One towed another Sea Pearl all the way back from the Dry Tortugas to Key West when the winds were light and fluky out of the east. Personally, I'd go for the lightest, smallest motor I could find. I'd like one light enough to stow in a locker for the 99% of the time when I don't need it. For me, the transom cut-out would make the most sense. the motor wouldn't be so far away and easier to lift. If you don't have the rear lazerette you'd be closer to the motor. If you do have one, you could store the motor in the lazarette.

[Ray Frechette Jr]

Storing a gas motor in an enclosed compartment or storing gas in an enclosed compartment would certainly require ventilation and bilge blower placement.

I would be loathe to do such.

[Peter HK]

Pick up a used outboard -something like a Tohatsu  4,5,or 6 hp 4-stroke

Engine shaft:  15" (short) or 20" (long)?

I'd second the call for the smallest, lightest outboard you can get. The motors you quote are about 25 kg (55lb). That's a lot of weight to lift and leave hanging out the back ruining sailing performance. You don't need much power- my 2 hp Yamaha 2 stroke weighs 9.8kg (21lb) and gets my CS17 to hull speed (about 5 knots) at 1/2 throttle.

I have a short shaft motor as the adjustable bracket puts it as deep as you want. In the photo from launch day you can see the up position; when fully down the lower edge of the motor board is just above water level. The in-between positions are good in shallow water

[hokeyhydro]

4-stroke storage. I believe a 4-stroke engine can not be stored laying down because of the oil problem.  They can be tilted forward like when you raise the engine all the way up, and allowed to turn to one side or the other to the steering stops, but not placed on their side.  Might be able to store them sort of flat on their nose.  Check your owners manual . . .

[Scott Dufour]

Thanks guys-

So it's  15" shaft, 2 hp. 

Bracket... something with a vertical rise of at least... what...  10 inches?