Motor sailer

[Dave MilbournParticipant @davemilbourn48782]

[Dave MilbournParticipant @davemilbourn48782]

I had an E-Mail from an old school mate this morning:

Some 25 years ago I built an RC model yacht for my children to play with using the Smeed plans for a Starlet. I rediscovered this a few months ago and have refurbished it for my nephew’s son who is 8. I guess at that age he is likely to find it difficult to sail the yacht against the wind so I decided that I would look into adding an electric motor and a propeller. So far I have not been able to find anything that would help in this conversion. Have you come across any models using both sail and propeller power? I guess the obvious problems are fitting the prop shaft and motor to an existing boat and needing a 3 channel RC system? I’m pretty sure I could overcome the first problem but I don’t have a clue about the second!

I've no experience at all of things with rags and sticks, let alone those which have motors to assist. What would you guys suggest as a suitable model for Peter's nephew?

Dave M

[Colin BishopModerator @colinbishop34627]

One point to consider is that. like Thames Barges, there is no need for the propshaft to exit on the keel line, it will be quite OK to have it sufficiently off centre to allow the prop clearance. This will make it a lot easier to install. A low drain 380 size motor with a 30mm prop should be fine I would have thought.

As far as control is concerned, the rudder (and motor if needed) can be used to tack the boat so I would imagine that all the third channel needs to do is to let the sail in and out.

There was an article in the magazine a while back which was on this very subject but I can't recall when.

Colin

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

A suggestion.

My thames barge is 48" long and carries near 1000 sq" sail. She probably weighs in at about 35lb. Her engine is a 6V decaperm with a 4 bladed 40mm brass propeller. I use a large SLA 6V for power and internal ballast as well as a small weighted keel. This motor is usually more than enough to "get out of danger". Plenty of power at low revs without any requirement for speed.

I believe the Vic Smeed "Starlet" is a 36 inch yacht, so would possibly be about 12lb in weight with (guessing) about 500 sq" sail all in use. She has already got an r/c system, so that will not be above 6V possibly only 4.8V. I suggest a 545 motor with 3:1 reduction and a 3 bladed 35mm prop, running from a 6V supply. The battery may have to be a heavier duty than already fitted. This should give enough power to bring her head round up to wind and make progress. Of course, a young lad will want speed to, but the combination should be enough.

[I know yachts are usually fitted with an egg whisk, 2 bladed, that collapses when not turning, but they are sailing yachts.]

I've never converted or adapted a yacht in this way, but in my attic I now have a name and design for my mystery yacht, which I think could be a Starlet, after looking them up on the web. I might even try my suggested conversion too on her and use her for sail training.

DM its not "rags and sticks," its "twigs and string with flappy bits" for a more technical description.

Just an idea, aye, Kim

[Colin BishopModerator @colinbishop34627]

I don't know if it is equally applicable to models, but trailing props, especially if locked and not free wheeling, create a lot of drag on full size ships which suggests that a small prop running relatively fast will be better than a large one running comparatively slowly. Just a thought!

Colin

[ashley needhamParticipant @ashleyneedham69188]

An 8 year old is likely to have the motor going all the time anyway, I know Berengar would have,

Could set the motor to "fast idle" with the trim to make it go round all the time and not degrade sailing performance? Small prop good idea, an X pitch must be less draggy when stationary than a brass or plastic three blader?

Dave, you are in the same boat (figuratively speaking, mind) as when I made the sailing Herald…masts?? sails?? booms and wotnot!

Ashley

[Dave MilbournParticipant @davemilbourn48782]

LIz says only real boats have propellers. Her idea of a real boat also includes many HP, a deep vee hull and at least two engines. She refers to masts as "those sticky-up things".
I've never been tempted to try one.

Dave M

[Kimosubby ShipyardsParticipant @kimosubbyshipyards]

DM, I'm ignoring any and all comments re yachts, from all persons! (Bob will be along next.)

I've just weighed my attic dweller, and she's 5.15Kg. So adding all the "top hamper" [look it up] that's about 5.5Kg afloat, maybe 6 with bigger batteries.

And can anyone confirm that this is the type of vessel we are discussing, a poor photo I agree, but is this a "Starlet"? Now you have the size, do you think a small prop is going to inhibit her drift?

Ashley has the right of it, any young fella with a boat having a motor is going to use the motor… And, quite rightly, he raises the requirement for another channel for the motor too.

Cheers and happy hunting Dave, aye, Kim

 

Edited By Kimosubby Shipyards on 14/08/2014 16:09:11

[Colin BishopModerator @colinbishop34627]

Certainly looks like a Starlet to me.

Colin

[Dave MilbournParticipant @davemilbourn48782]

It does to me, too. Many thanks, chaps. I hope Peter is now following this.

Dave M

[Peter RueParticipant @peterrue26012]

I am the Peter to who Dave referred in his opening post and I too do not want to get into the argument about power v sail, especially as I want to add power to sail!

Thank you all for your comments and suggestions. I would never have thought about an off centre propeller or the drag caused by it while not rotating.

To answer Kim, yes, that is the Starlet and I have included a picture of mine. Now that you have looked at your dry docked model, do you think that there is room to put in a suitable motor? If so, which one, where and with what controls? Dave has suggested the alternative of making a new boat from scratch so if anyone has any suggestions for a plan or kit suitable for both power and sail I would be very grateful to hear them.

I am principally a "wood worker" so the only experience I have of electronics RC is from the 20 year old Starlet. Technology has moved on a little since then! Any advice about servos and control systems for this project will also be vey welcome.

Peter

[Peter RueParticipant @peterrue26012]

I just found this on a site called Scale Hobbies. Since its for a folding prop to reduce drag, it looks as if I'm not the only one stupid enough to want to do this! I would really appreciate any comments or suggestions about ths approach.

Peter

[lnvisiblemanParticipant @lnvisibleman]

Please correct me if I am wrong but is this an extract from an oriental site?

The astounding translations never fail to have me in stitches.

Mike

[Dave MilbournParticipant @davemilbourn48782]

This is one of the former Graupner marine motors with a gearbox which has been dropped since Graupner changed ownership. You'll be very lucky to find anywhere with one left in stock. It's a shame because having the motor mounted integral with the shaft would make installation so much easier.

However I've always thought of it more as a "get me home eventually" device rather than as an alternative to sail. I'm not sure how much headway you'd make into the wind without tacking.

DM

[Andy CParticipant @andyc56856]

Don't full size yachts Have a very small (compared to the size of the yacht) outboard on the rear stern but over to one side. Seems to work for them ok.

Andy

Edited By Wraith Leader on 15/08/2014 16:22:05

[Peter RueParticipant @peterrue26012]

Dave, I will ring Scale Hobbies tomorrow (not open I the week) to see if they have one but since they don't list a price I suspect you are correct about availability but worth a phone call.

Andy, another good idea, thanks.

Would it be possible to rig a servo to tilt the outboard out of the water when using sail? That would be fun!

[Dave MilbournParticipant @davemilbourn48782]

Peter

Try 'A Model World' as well. Mark Williams was one of the main Graupner importers until the brown stuff hit the whirling thing.
Your servo idea is relatively easy, given the availability of outboards.
I have a couple of Aeronaut 3v outboards from Mark W, which might be useful. Not cheap.
A copy of the plans would help ……………………pretty-please, anyone?

DM

[Peter RueParticipant @peterrue26012]

Dave, I tried to scan and assemble the plans last night but without success (I do wish I had bought that A3 scanner!). I can certainly send you the plans by post if that would help? My current thinking is that I will use a reasonable power inboard motor (with appropriate speed control) set off centre and join the propshaft to the motor using a flexible coupling. I'm comfortable with the mechanics of this but can I please have suggestions for:

motor

speed control

shaft

radio control sysytem

Thanks

Peter

[Peter RueParticipant @peterrue26012]

Sorry, forgot to add what type and capacity of battery!

[ashley needhamParticipant @ashleyneedham69188]

I purchased something similar for the Sunderland but it was very noisy, as the tube is just that, a bit of tube and not something with bearings in either end..I eventually fitted it on the Herald, as the compactness of it is ideal for this application and the noise is acceptable for occcaisional use.

Ashley

[Peter RueParticipant @peterrue26012]

Thanks Ashley. It sounds very much like I should do this properly with good equipment. Apparently it is possible to get folding propellers to fit standard shafts.

Peter

[Dave MilbournParticipant @davemilbourn48782]

Peter

I'll E-mail you tomorrow.

Dave

[Dave MilbournParticipant @davemilbourn48782]

I've come across Model Marine International plan MAR3022 "Ardent", which looks as if it would readily accept a motor conversion (if it doesn't already have one). Does anyone have this plan or MMI May2003 issue so that I could confirm this, please?

DM

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