Swallow Yachts Association
Swallow Yachts Forum => General Discussion => Topic started by: Terry Cross on 24 Sep 2009, 23:55
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Just arrived back from Ullswater after a fantastic days sailing and trying out our prototype electric outboard mounted on the rear of the rudder. It performed a lot better than expected. Not wanting to spend a lot of money on something I did not think would work, I bought a cheap
outboard (seasnake 34lb thrust),made up a bracket out of scrap 9mm ply and used the caravan battery placed in front of the centerboard case with jump leads to connect to the motor.
We motored out of the marina, set the sails,lifted the outboard clear of the water and sailed all afternoon
with the motor perched unobtrusivly on top of the rudder.
Later we furled the sails and put the motor through its paces. With 2 adults and a heavy battery onboard it maintained 4mph on full power, (2mph in reverse)
It is highly manaeuvreable and does not appear to put undue strain on the rudder or pintles.
I must point out that last year I fitted an extra pintle to the top of the rudder as I felt that there was too much "play" a this point (this also required the SS pivot bar to be extended.
Hope to post photos soon
Terry Cross
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Here are my dad's photos as promised. (he gave up and emailed me insted) Please bear in mind this is a prototype/feasability test.
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I forgot to mention...the pics also show my fathers response to my moans about the play in the original tiller/rudder arrangement. He has added an extension to the long rod/pintle and a third gudgeon to the rudder.
The rudder, when lowered, drops onto the extension, eliminating the play which otherwise is amplified by the distance from the top gudgeon to the tiller. (hope that makes sense). It gives a far more positive feel to the helm. In my opinion, this is the best thing that we have done to the boat since we've owned it.
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The Watersnake is not an electric motor I had heard of before. I've found some comment on an Australian fishing site which compares it to the Minn Kota. It appears to be cheaper bit some say it isn't as well built & not as resilient to salt water.Others disagree. I'd be interested in your views, where did you get it from.
I had decided that I would go for small 4 stroke on my eagerly awaited BR17 but do like the idea of electric if I could find a suitable machine.
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Paul, Terry
Neat stuff all round. Thanks for sharing it all, and for the super-helpful pics. I am particularly interested in your cunning modification of the rudder suspension, being a bit disconcerted myself by the degree of play in the steering. Two practical questions - 1) Where did you get your extra pintle from? (Mine are bronze, came with the kit) 2) How does a non-engineer like me go about extending the SS pivot rod? I suspect the answer is that I don't, but kindly advice would be much appreciated.
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Graham
I am not very knowledgable about electric outboards. I purchased the Seanake from Tacklebargains.co.uk who appear to have a variety of makes at very competetive prices
Terry
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Michael
The gudgeon, I wrongly called a pintle, was purchased from Classic Marine. Thats the easy bit.
I asked a friend of a friend to extend the SS pivot,he in fact made a new one. I should think any small eng. firm would help you out.
In retrospect I would have had another boss(the brass bit that stops the rod falling through)fitted just below the new gudgeon to act as finger pull to remove the rod. If you look closely you can see that I have fitted a black ring to act as a pull.
Terry
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Hi Paul and Terry
I apologise to everyone else for dragging a thread probably of little general interest to the top of the pile, albeit presumably briefly.
Belatedly, having been preoccupied with re-rigs, moving house etc, I am modifying the rudder mounting on my Storm Petrel along the lines described and illustrated by you both in September last year. I can see that the elimination of the side-to-side play in the steering makes a lot of difference. However, in assembling my new set up I ran into an immediate problem which close examination of your pics hasn't resolved for me. It's doing my head in (to coin an expression no-one has ever used before): help please!
I haven't bolted the third rudder gudgeon on yet. I can only assemble the whole thing by putting the gudgeon in place last, and then the rudder can't be dismounted! Sliding the pin upwards, the extra (upper) brass boss, which you advised would help, comes up against the underneath of the new uppermost rudder gudgeon before the pin frees the lower gudgeon pairs (one each from rudder and sternpost), and so the rudder can't be lifted off. There's a similar problem if I try to lift the rudder off the top of the pin (a continuation of the process illustrated in the last-but-one of your photos posted on 28/9/09). I have tried every which way - I think.
I think the problem must be caused by the much longer sternpost on the S15 than the SP, and the corresponding differences in the distances between the various gudgeons (all the same, having had my difficulty, and from the photos, I can't for the life of me see how you get Iona's rudder off the boat - you don't leave it permanently on, do you??!!). I also think/hope that removal of the extra boss will enable me to slide my new pin upwards enough so that the rudder can be dismounted: fortunately the boss is fastened in place by a sort of spring pin which I can probably knock out.
Am I being a complete idiot? If so, please let me down gently, but if you can tell me what I'm doing wrong, I would be grateful! Then this thread can sink down the lists again. In any case, I doubt whether anyone other than a S15 or SP sailor will have the slightest idea what I'm on about.
Help!
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Michael
You are not being a complete idiot.
Iona's new assembly has just enough play in it to allow the rod and boss to miss the top gudgeon if the rod is lifted from the bottom gudgeon and moved out of line. The rod can then be removed as normal.
I had originaly envisaged a boss with a grub screw to get round that problem but my dad found that this was not neccesary when the new rod arived (with boss already braised on). A Removable/repositionable boss my be your best option for the Storm Petrol.
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Thanks, Paul. I am reassured on the competence ( and sanity) front, and grateful for your help
There isn't enough play in my system, presumably because the inter-gudgeon distances are less on the SP. I've removed the extra boss, and that doesn't help, the pin still can't slide up far enough. And I don't want to be fiddling around with grub screws or whatever when launching.
I think I've worked out what to do. 1) A rod which is long enough to take a boss above the new rudder gudgeon, right at the top. This obviously stops the rod slipping down. 2) Re-engaging the existing spring clip either into a notch in the side of the rod itself (with an orientation mark on the top boss), or into a circumferential groove: it should be possible to get it to engage without significantly weakening the rod, and positively so that the rod can't ride up. Operating the clip as per usual will then allow the rod to be fully withdrawn, past any gudgeons in the way.
With my newly acquired (and removed!) bosses + pins, all I need now is another length of 10mm 316 s/s rod, and the ability (which is questionable) to drill the right sized hole through the rod at its top end to pin (or grub-screw, I suppose) a boss on. What's the best lubricant for drilling steel?
I think the gains will be worth it, although you must have had more play in the old set-up than I have. The new system has a splendidly 'taut' feeling in comparison.
I'll see how I get on. Watch this space, but don't hold your breath.
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Quote from Gareth Curtis July 6th
“My problem is that I want to take my kids sailing and its all coastal sailing where I live. an outboard rightly or wrongly gives me a sense of security that I can get out of a difficult situation should I need too.
Have you used you electric motor in such a situation?”
We took “IONA” to the National Sailing Center at Portland last week.
As we launched from the slip and had a “fresh” wind all week we did not need the motor, however one day we visited Weymouth (three adults aboard). On approach we started the motor and furled the sails. It took us up into the harbour ( against the current and the wind) at about 2.5 mph. We manoeuvred easily around the harbour and made our way out at about 6 mph. and it held the boat into the wind whilst the sails were re-set.
Terry
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After two seasons of using the prototype and “ironing out” the snags I have finally arrived at the finished article (I think)
I always found it difficult to lean over to lift and /or tilt the motor out of the water.
Some sort of up haul was required. Running a line from the motor mount down through a block attached to a clamp on the leg, back up over the mount and terminating at a jamming cleat on the tiller achieved this.
To keep the control arm always pointing forward I made a wooden guide that also acts as a crutch for the yard and base for a flagpole.
The whole rudder can still be lifted for launching. To assist with the extra weight I have fitted a block in the lifting line.
The motor has been invaluable, especially last month when I had a pontoon berth in Portland Marina. This meant motoring out through hoards of Olympic hopefuls, finding a patch of clear water and finally hoisting the sails.
Terry Cross “ IONA”
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Piccies for the above comment.......
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Hi Terry, am I correct in thinking that the bottom end of the motor is too large to consider sticking through a hole in the outboard well?
I am currently building a Storm 15. Mostly going well although a few parts don't seem to be the right size. Hoping to get it wet before the winter. Where did you launch on Ullswater? We will probably do most of our sailing in the Lakes as it is fairly local.
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Hi Steve
Good luck with your build .You will not be disappointed
In my opinion the outboard well on the Storm 15 has many disadvantages.
Unlike the Storm 17 the design does not allow the motor to be tilted to clear the water.
Even if the aperture were big enough to accept the base of an electric motor, by raising it the tiller would be fouled.
The “hole” in the bottom causes lots of turbulence and impedes the performance. I have an Eagle 525 trailer sailor with an outboard well, which I have “blocked off” and placed the motor on the transom where it can be lifted to clear the water. This gives me an extra one and a half MPH when sailing.
The builder of “IONA”, Bob Jennings, “could not bring himself “ to cut out the ”hole” We are relieved he did not. (An account of the build is featured on the forum. Last post Aug. 13th 2009)
We use Ullswater Marine. William Grundy is always ready to help.
Terry Cross “IONA”l
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Hello, all you electric lot
Not of particular interest to me, but following a phone conversation with Pete Greenfield (editor/publisher of Water Craft), the following might cause a spark or two -
1) You may be aware of the 'Cordless Challenge' at the Beale Park Show this year, being a series of races for boats powered by (the electric motors of) cordless tools. It was won by a young man from Germany, married and resident in UK: his boat was probably several knots faster than any of the other boats which competed, and he won by a huge distance. He used a model aircraft, rather than outboard, propeller. The competition was covered on the UK HBBR Forum website. Jeremy, who contributes knowledgeably to this forum, had his entry ruined by a spectator who switched the motor on while the boat was on terra firma, apparently to see whether it was any good for ploughing. Shame his carefully designed craft couldn't compete. Both Jeremy and the competition winner (whose name I do not have to hand) are scheduled to have articles on the Challenge in one of the next few issues of Water Craft.
2) Pete Greenfield tells me that there is great interest in electric outboards in Finland, where the first thing that knowledgeable users do, having bought their electric outboard, is to fit a model aircraft propeller from the nearest model shop, in place of that supplied with the outboard.
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I'm afraid that my article in the next issue of Watercraft isn't very Swallow Boats related (although the next article from me will be).
It's very true that changing the prop on an ordinary, cheap, electric outboard will significantly improve efficiency, as I have mentioned here before. An acquaintance from another forum has undertaken some very interesting experiments to show the improvements in performance that are possible by modifying a cheap electric outboard. They are documented here on this Boat Design forum thread: http://www.boatdesign.net/forums/boat-design/efficient-electric-boat-27996-15.html#post302305 and the subsequent follow on post by MCDenny.
Jeremy
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I've had a look at this idea too...(never ignore the Finns)
The idea of switching for a model aircraft prop seems to be centered on(or should that be "revolve around" ?.....) very lightweight craft..ie canoes, kayaks etc. I suspect that, as most electric outboards are designed to replace small petrol models, their props have been optimised for the largest craft that they could reasonably be bolted to the back of. Consequently there may be large gains in efficiency to be had when using them on very low displacement boats.
IONA is probably at the top end of the "comfortable with a cheap electric outboard as a means of auxillary propulsion" range of boats.
Swapping out the prop may not yield much but at around £5-8 for a suitable model aircraft propeller...I feel an experiment coming on..........
Paul
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Denny Wolfe's experiments (the link I gave above) were aimed at propelling a fairly high displacement sailing boat, of around 14 to 20ft LOA.
Having done a lot of experiments myself I can confirm that a correctly sized narrow blade prop, like a model aircraft one, is massively more efficient than a typical outboard prop.
The downsides are that the long thin blades are relatively fragile, plus they tend to collect weed. Outboard props (and boat props in general) seem to be optimised for small diameter (for reduced draft) and good weed shedding properties, both things that very significantly reduce efficiency.
There is a way around the weed fouling problem, by making the blades fold, like this prop I made a while ago, for one of my experiments:
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Further to the above, I've attached a graph that Denny Wolfe derived from some testing of a Minkota electric outboard modified with a fairing around the tubular leg (to reduce drag) a 10 x 6 APC model aircraft prop, a model aircraft spinner (again to reduce drag) and a model boat PWM speed controller instead of the rather lossy resistors that some of these motors normally use.
I've also borrowed a couple of photos that Denny posted on the Boat Design forum thread that illustrate the mods he made to his motor.
http://www.boatdesign.net/forums/attachments/boat-design/35904d1254966402-efficient-electric-boat-img_2187.jpg
http://www.boatdesign.net/forums/attachments/boat-design/35905d1254966402-efficient-electric-boat-img_2185.jpg
The performance improvement he obtained from these mods was pretty good. Denny kindly detailed the performance change with each of his mods (the speed setting numbers in the first three tests refer to the Minkota speed settings with the switched resistor control):
Baseline with unmodified motor:
-Speed #5 (WOT) gave 4.3 mph at 330 watts; range 1.7 hrs, 7.3 miles.
-Speed #4 gave 2.9 mph at 178 watts; range 3.4 hrs, 9.9 miles.
Switching to an APC 10x6 prop:
-Speed #5 gave 5.1 mph at 410 watts; range 1.3 hrs, 6.6 miles.
Adding the PWM controller and adjusting 'throttle' to give 4.3 mph speed:
-Standard prop pulled 330 watts; range 1.7 hrs, 7.3 miles
-10x6 prop pulled 260 watts; range 2.2 hrs, 9.5 miles
-10x6 prop plus fairing and spinner pulled 190 watts; range 3.2 hrs, 13.8 miles.