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Am in process of building a Sea Queen, but not with supplied motor, will be fitting a brushless. Based on the motor and the voltage it is likely to be about 400 watts output, which is about 5 times the supplied output. My concern is the supplied prop shaft which is 18" long and 4 mm dia. is there likely to be 'whip' in a shaft of that length ?
Was considring a larger diameter, but that brings in the problem of obtaining propellors M4 and M5 are common. Or can one get prop shafts with centre bearings.
What have other people done ?
Or are my fears unfound, I remember the days when prop shafts were mild steel not stainless and bent easily.
Is the boat built??? if so try moving the motor towards the stearn, lower the shaft angle, this allows the prop to deliver more thrust to propel the boat, the original boat was designed for an I/C motor with a big flywheel, so needed plenty of clearance from the keel. Measure the distance you have moved the motor and push a dowel etc into the hole for the shaft, deduct the size for the U/J, you then have the size of the shortened shaft lenght
Hi Andy What size is your Sea Queen? Is it from a kit or a published plan? What particular motor, ESC, battery and prop size are you intending to fit? If the supplied prop shaft is true it should be OK. I suggest you test it by removing the inner shaft and rolling it on a piece of glass. Any bend will easily show and that shaft will be unusable for your purpose. As Jarvo says you can perhaps shorten the length. I have just looked on the Cornwall Model Boats site and they have 5mm prop shafts which may be a better quality than those you have and are supplied with the common prop threads. Modern prop shafts are much better than were available a few years ago and yes I still have (unfitted) the original aluminium and mild steel prop shafts for my Aeorkits Solent 48" lifeboat and they were both bent!
Moving motor to rear, I thought that would increase the shaft angle, though it will shorten the length of the shaft?
The Sea Queen is I think 46", kit, overlander 5045, 6250 mAh 3S LiPo, Fusion hawk HV 60 esc (not sure but this might be better with 80 or 100), [expect power about 400W], prop 45 / 50 / 55 mm (not sure which to start with, might start with 45 mm). Been looking at a shaft from Deans models.
Hi Andy, as the boat is in kit form, just get the keel sections, on the drawings they tell you to leave a gap to fit the prop shaft. re-adjust the angle of the gap to about 15 degrees, this will give you room for the motor mount and the length of the prop tube, give yourself enough clearance for the largest prop, 55 - 60 mm, with the motor you are looking at i would go for the 100amp esc not much extra but a lot more security, power wise. Prop shaft, have a look at the Raboesch ball raced shafts from Deans Marine, very good at higher revs.