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[artisan100]

I've been slowly working my way through updating a Weser for the past year or so, and have now fitted lights, got the pump working, etc, so it's time to look at the propulsion system. The boat is designed to have three Graupner Speed 500E motors but my boat (bought secondhand) came with one large unbranded motor driving the middle prop off 12V, with the outer two props just connected to the propshafts but no motor.  All three props are plastic, but the middle one is bigger than the other two, but I don't know if that is a later fitment. My intention is to add the two missing motors and play around with various mixing options, but what should I do about the props - leave them all as they are or change over to brass ones. And if so, how do I determine what spec I want?

By the way, can anyone tell me which way the props are supposed to rotate on the original kit? The Graupner site no longer has a link to the instructions.

TIA

Geoff

[n33h]

looking at the photo, the letf and middle prop turn clockwisee (right hand) and the right one turns anti-clockwise (left hand) does'nt matter which way the turn

if the props are the correct size for the boat then stick with the same size and get them in brass, you'll find the brass props have a bit more pitch than the plastic ones and they'll speed the hull up (by about 1mph)

if they have the size on the back of the prop then you know what size to get, if not then i think its

measure from the hub of the prop to the tip of one blade and this should give you the size you need

[DickyD]

From hub of prop to tip of blade is half the size of the prop. 

[artisan100]

Thanks guys.

Is the pitch standard then? And is 3 blades the correct way to go?

Geoff

[DickyD]

http://www.cornwallmodelboats.co.uk/acatalog/raboesch-brass-propellers.html

All you need to know, type of prop for which type of boat, you just need the shaft diameter.

[artisan100]

Many thanks. I'll get my calipers out.

Geoff

[sandy1000]

I have a model of an 1873 twin prop warship. Both props rotate the same way.  I am trying to avoid correcting this and so does any one know when twin props were introduced and were they contra rotating from the start or was there a period, hopefully including 1873 where they were both rotating in the same direction. This is a complete cop out on my part but if history shows that my twinscrew lashup is OK then I have saved a lot of remedial work.

[n33h]

IMO, i like to use counter rotating props because they cancel out prop walk to eachother, if you decide to use different props just switch the motor leads round on one motor so it spins in the opposite direction

nick

[DickyD]

I have a model of an 1873 twin prop warship. Both props rotate the same way.  I am trying to avoid correcting this and so does any one know when twin props were introduced and were they contra rotating from the start or was there a period, hopefully including 1873 where they were both rotating in the same direction. This is a complete cop out on my part but if history shows that my twinscrew lashup is OK then I have saved a lot of remedial work.

As Nick said, no big deal, all you need do is change one prop and switch your cables over on one motor.

[sandy1000]

There is a solution somewhere, thanks for the suggestions.

[n33h]

i use gold plated bullet connectors on my motors (depending on wire gauge depends what bullets i use, IE - 16 gauge wire would have 2.5mm bullets) so it's much easier to switch motor wires if needed, if its multiple motors then i use a choc block (terminal block, usually upto 30A again depending on wire used)