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    Followers
    Vosper 46" fire boat motors and prop
    by Schmango ๐Ÿ‡ฆ๐Ÿ‡บ ( Able Seaman)
    ๐Ÿ“ฃ










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    24 Posts 23 Replies 19 Photos 41 Likes
    ( Newest Posts Shown First )
    Colin H
    Vice Admiral
    ๐Ÿ“ Vosper 46" fire boat motors and prop
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    Country: ๐Ÿ‡ฌ๐Ÿ‡ง United Kingdom
    Online: 23 minutes ago
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    Your model looks good on the water, I have a similar problem on my old aerokits 34.5 inch version due to the fact it was originally ic powered and the angle of the propshaft is too steep, this tends to lift the stern as it pushes.
    Also I found that by increasing the size of rudder helped in the turns.
    In the pictures of my Norstar 34.5 inch version I have lowered the thrust angle, the prop is a 40mm 3 blade brass, and the rudder is 50mm deep, set with a 25 mm spacing to allow for the water pick up and easy prop change.
    I am also thinking of fitting the rudder with a horizontal fin on the bottom to help stabilise the thrust .
    Cheers Colin.
    3
    Fair winds and calm waters, COLIN.
    canabus
    Midshipman
    ๐Ÿ“ Vosper 46" fire boat motors and prop
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    Country: ๐Ÿ‡ฆ๐Ÿ‡บ Australia
    Online: 19 days ago
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    Hi Schmango

    I have my two 3S 4000mah Lipos mounted each side of the rudder.
    That's the only way I got mine to turn better.
    The boat is not great on the turns at the best.

    Props, try Float a boat in Melbourne.
    Canabus
    3
    Schmango
    Able Seaman
    ๐Ÿ“ Vosper 46" fire boat motors and prop
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    Country: ๐Ÿ‡ฆ๐Ÿ‡บ Australia
    Online: 17 days ago
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    Hi all - finally got to sea trial this today . The most notable issue is shaft alignment which is why it sounds like a two stroke engine . The 5mm shafts are very old and have some pitting in the metal which is strange. There is a small amount of play with them which Iโ€™m guessing is causing the noise . The motors are cheap 700 size drill motors from eBay which do the job I think. Props are 45mm but I couldnโ€™t find counter rotation in 5mm props so they are the same which isnโ€™t a big issue.

    Turning circle is terrible and it wants to nose dive even though the lead acid battery is towards the aft. Looking at other models of this boat it seems to be common though ? Is it normal to have the props and rudders a fair way apart as per the pictures?
    I restored this model so I donโ€™t know itโ€™s history or age - it has definitely been built by an amateur and was possibly petrol powered once. Iโ€™m guessing itโ€™s from the 1970 era .

    Overall itโ€™s a great boat and Iโ€™m happy with it .

    https://youtu.be/Ac-DaFtMJgw

    Cheers
    https://youtu.be/Ac-DaFtMJgw
    ๐Ÿ”—
    3
    jbkiwi
    Fleet Admiral
    ๐Ÿ“ Vosper 46" fire boat motors and prop
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    Country: ๐Ÿ‡ณ๐Ÿ‡ฟ New Zealand
    Online: 9 seconds ago
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    The 4.8s are as good as 5s and would only require a bit of clearing out. I would run a 5mm drill in reverse through them which should make them a good firm fit or just give them a touch with a needle file. See if you can make a jig with close fitting dowels to stop them spinning and use a blunt drill to stop it biting, (you can take the edge off by gently drilling a concrete block for 1 sec) - start off with say a 4.2mm drill, then 4.5 etc and work your way up to just undersize, then use a 4mm reamer to finish it off. less chance of getting a bit off square. Bit harder without a drill press but it can be done. I'd go for a 4.8 if you can find the right diam. Use leather gloves to hold the prop, not your fingers, (you'll see why if you don't.)๐Ÿ˜ฎ๐Ÿ˜ญ The 4.8 is so it fits on the thread of the shaft,- you might find that you can just line up the shaft and screw it into the 4.8, fit a nut and that's it, - may have to only drill a small depth at the front of the prop to clear the shaft to show enough thread for the nut.

    JB
    2
    Ianh
    Commander
    ๐Ÿ“ Vosper 46" fire boat motors and prop
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    Country: ๐Ÿ‡ฟ๐Ÿ‡ฆ South Africa
    Online: 2 months ago
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    Be aware some motors available chow power at an alarming rate
    1
    Only old in years not mind or soul.
    Schmango
    Able Seaman
    ๐Ÿ“ Vosper 46" fire boat motors and prop
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    Country: ๐Ÿ‡ฆ๐Ÿ‡บ Australia
    Online: 17 days ago
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    Thanks for this info but I couldnโ€™t find any 5mm - they are 4.8mm surely they are not the same ? Anyway I will have a look at drilling out a 4mm and using a lock nut . My concern drilling is getting it out of centre as I donโ€™t have a drill press.
    1
    jbkiwi
    Fleet Admiral
    ๐Ÿ“ Vosper 46" fire boat motors and prop
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    Country: ๐Ÿ‡ณ๐Ÿ‡ฟ New Zealand
    Online: 9 seconds ago
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    Hi Murray, as previously mentioned, there are a lot of 5mm props on Ali Express in left and right hand. You can drill a 4mm prop out to 5mm without any problems also (there are tons of 4mm props on the site as well) Not sure why you would want to change the shaft. The store shown has a good selection of props. Just bore a 4mm prop out and use Nyloc nuts and a drive dog (you can cut notches in the front of the hub) with a Teflon washer behind the prop. LocTite the nuts on if you are worried.

    JB
    2
    Martin555
    Fleet Admiral
    ๐Ÿ“ Vosper 46" fire boat motors and prop
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    Country: ๐Ÿ‡ฌ๐Ÿ‡ง United Kingdom
    Online: 5 hours ago
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    Hi Murry,
    Your idea of the prop end conversion is very unusual and i have not heard of this being done before.
    However i still think that you could end up with wobbly props.

    As for having a pair of the same handed props i would imagine that a bit of rudder offset will be required.

    I am by no means an expert and would also like to hear other members thoughts on this.

    Martin555.
    1
    If it looks right it probably is.
    Schmango
    Able Seaman
    ๐Ÿ“ Vosper 46" fire boat motors and prop
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    Country: ๐Ÿ‡ฆ๐Ÿ‡บ Australia
    Online: 17 days ago
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    Hi - I have the motor thatโ€™s in the pictures I posted - it has similar specs to a graupner 700 but is out of a leaf blower ๐Ÿคฃ.
    I found an m5 45mm prop but not a counter rotation option so I will ha e to see how it goes with two right hand rotations . Anyone noticed much prop walk/ torque issues here ?
    As a back up I have also purchased two 5mm to 4mm shaft couplings which are designed for motor to shaft applications but I might try and adapt them to the prop end by cutting an m4 screw for the prop end and attaching the prop that way if the props I have ordered donโ€™t work.

    Thanks for your help - itโ€™s greatly appreciated
    Cheers
    Murray
    1
    Ianh
    Commander
    ๐Ÿ“ Vosper 46" fire boat motors and prop
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    Country: ๐Ÿ‡ฟ๐Ÿ‡ฆ South Africa
    Online: 2 months ago
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    It work hardens like a devil even 316. I know being a Mining Engineer๐Ÿ˜€๐Ÿ˜€
    1
    Only old in years not mind or soul.
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