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Thread: Wanting to twin a DF 28 Pathfinder

  1. #1
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    Default Wanting to twin a DF 28 Pathfinder

    Hi Y'all!

    Since racing in Canada is most likely a thing of the past and the border shows no signs of opening this summer (or sock boy is still in hiding..) I have decided to take a partly finished single drive Pathfinder and gut the crap build I did for an inlay and a twinning.

    I was thinking of this speedmaster rudder https://www.offshoreelectrics.com/pr...s-spdrs-009-du

    And I was thinking of TFL 3/16" Hydro struts https://www.offshoreelectrics.com/pr...prod=ose-80046 to be cheap... or should I not be cheap? The ones in the link are only 1/8" bearing but TFL makes them in 3/16".

    Any other suggestions?

    I have a pair of 2 pole 36mmx60mm motors to start. They are Feigao knock offs, cheap as chips when I bought them. I also have a pair of Swordfish 120A 2-6S esc's to start with as well. I may go to some Proboat blue motors possibly that I have as spares for racing....

    It has lots of room inside for parts and doing work. I'm curious as to how far back to mount the motors?

    Help and suggestions are appreciated!

    It's basically for fun, needs to handle bit of rough water...
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  2. #2
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    Hey nice Ray, as of late I have been missing my Old Geico twin. This should be a comparable project.
    Hope all is well for you on that side of the country, we have no5 spoke in awhile.

    Shawn

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    Very nice to hear from you Shawn, specially these days when things are a real pain in the arse here as well as your side of the country.

    I'm surviving. Good day today! As long as I keep tinkering I should be alright. I hope you are doing well too.

    Cheers!
    Nortavlag Bulc

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    Tenshock rudder is ferfect, different size available

    Prefer strut with 2 screws :

    https://www.mini-meca-rc.com/121-strut


    Last edited by Alfa Spirit; 04-10-2021 at 05:37 PM.

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    Me Likee!!! Thank you! I will look...
    Nortavlag Bulc

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    Hmmm, the link doesn't show those rudders. It shows struts etc but no Carbon rudders.
    Nortavlag Bulc

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    I'm going to run this on a pair of rewound gold AQ motors Don H. did for me. They are 1950KV and I hope I can turn 1815's on these motors because that's the props that are available in the size range that I don't have yet.

    Will the 1815-17 ABC's be too much or O.k. for a 2 or 3 minute run on 4S2P 10K total?
    Nortavlag Bulc

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    I would think the AQ’s would turn them Ray, especially under 2k and on 4s. Building a twin is supposed to let you ‘up the Aunty’ in prop selection compared to what you would push the same boat in single format. Twins will help each other push a larger prop.

  10. #10
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    Thanks Shawn. I will place an order to OSE shortly. I'll try the PB SS 1716's first that I have and try the larger ones after.
    Nortavlag Bulc

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    following
    2008 NAMBA P-Mono & P-Offshore Nat'l 2-Lap Record Holder; '15 P-Cat, P-Ltd Cat 2-Lap
    2009/2010 NAMBA P-Sport Hydro Nat'l 2-Lap Record Holder, '13 SCSTA P-Ltd Cat High Points
    '11 NAMBA [P-Ltd] : Mono, Offshore, OPC, Sport Hydro; '06 LSO, '12,'13,'14 P Ltd Cat /Mono

  12. #12
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    1950KV twin? I bet you could run them on 6S.
    Cheetah, Super Rio, (Mod) Starship (Mod and sold),

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    Quote Originally Posted by larryrose11 View Post
    1950KV twin? I bet you could run them on 6S.
    C?mon Larry, let?s not make a 30? bullet

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    Maybe. I don't have 3S or 6S packs.
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    If you think Larry Jaques is slow, I just got my inlay done, lol...

    What next? I guess mount the hardware. I am going to fashion a carbon plate to cover the ugly holes.

    I have a Speedmaster mini dual intake rudder and a pair of TFL 3/16" hydro struts with lead teflon... for now. I might convert to Speedmaster type bushings and get rid of the teflon but the struts have some funky finished ID's, maybe metric??

    The inlay didn't go as easy as I'd hoped and as a result it's not as high up th inside walls as I'd like but it will do. I filled the holes first with a mix of epoxy, chopped glass and carbon fiber dust so it's solid.

    I was debating whether or not to make a carbon plate for the whole back transom below the seam but it's not needed.
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    Looks good Ray. Haha can I join the slow man group? It would be all Canadian content

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    I remember a fast Genesis with 8S batteries and 1300kV motors, good autonomy too, 8S for both motors. He used HobbyWing 80A HV escs.

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    Quote Originally Posted by Alfa Spirit View Post
    I remember a fast Genesis with 8S batteries and 1300kV motors, good autonomy too, 8S for both motors. He used HobbyWing 80A HV escs.
    I remember that too.
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    O.k. I have the struts mounted and rudder mounted too. The struts are adjustable in height and angle.

    My question to twin builders is how low do you mount the strut? I mean I could build flooded stuffing tubes but prefer it more simple and clean. Props will need to be angled down some since they are ABC 17 series props and the Stainless steel Proboat props first.

    Where to drill these holes???

    4mm of height adjust-ability.
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  20. #20
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    Ray
    I would say that your struts should come down a little.

    The first picture is of my 6S twin, struts are down 2 Degrees (I may lower this one some more)
    Second picture is of my 8S twin, struts are down 2 3/4 degrees.
    The ruler is 24" long and sitting on all three ride pads.

    If for example that your strut measures 1/8" from the bottom rear to the bottom of the 3/16" drive shaft.
    On a flat surface set the boat on four pads of 1/8" thick.
    Now with the struts set at 2 degrees, lower them untill the bottom edge touches the flat surface.
    At this point check to make sure that the tube will clear the inside bottom of the hull.
    If not you will have to rise them a little, if it is a lot you may want to consider longer struts.

    Larry
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    Bump & Grind Racing Props -We Like Em Smooth & Wet

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    Thanks Larry, I'm reading it over. Sorry I missed your call last night.

    So you measure the strut angle with your digital gauge like I have and you do it from the bottom?
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    Well... looking at pics of Larry's old MM twin, he had to put the batts on top of the tunnel and I don't want to.

    While test placing everything in the hull to see where the CG is it becomes evident why Larry had to put them there on a 29" cat. I remember in the past Ken Joye built a Drifter M or L and he put the pair of motors on top of the tunnel instead and I think I'm going to fill in the 4 holes I already drilled and put the struts right about here instead.

    The motors will be easier to install, maintain or change, the batteries then have ample room to move around in the sponsons for proper CG while keeping weigh low. I will be using a pair of brass Metric stuffing tubes because the TFL struts are bored out to 7mm Metric and from a 7mm tube to 6mm tube the Teflon tubing still fits properly inside for 0.150 cables. Using long stuffing tubes allows all the strut adjustments I could ever need.
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    Quote Originally Posted by larryrose11 View Post
    1950KV twin? I bet you could run them on 6S.
    I'm thinking about this now too. We will see after it's done.
    Nortavlag Bulc

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    Well, it's finally time to mount the servo and finish this thing.

    I was thinking of using a pair of Sullivan golden rod cables going through brake cable sheathing.

    Would that then be push pull or pull pull? Is there a draw back if it is pull pull? I want to use 2 cables but not if it's inferior to a thick single solid rod.

    Help??
    Nortavlag Bulc

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    Slowest build in the world??? Perhaps...

    I'm just figuring out cooling lines and some wiring ideas but it's pretty much done.

    I want to try PB 1716's I have first but besides those I have no idea what to choose for 4S power through a 2200kv.

    If I stay with 1.7inch props or smaller I can use my Hughey flex cables. If I go to a 1814 or so then I need drive cables with longer stubbs.

    Any help with props is appreciated.
    Nortavlag Bulc

  26. #26
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    Any help with props is appreciated.



    https://www.youtube.com/watch?v=JgRzweFct0M

    2008 NAMBA P-Mono & P-Offshore Nat'l 2-Lap Record Holder; '15 P-Cat, P-Ltd Cat 2-Lap
    2009/2010 NAMBA P-Sport Hydro Nat'l 2-Lap Record Holder, '13 SCSTA P-Ltd Cat High Points
    '11 NAMBA [P-Ltd] : Mono, Offshore, OPC, Sport Hydro; '06 LSO, '12,'13,'14 P Ltd Cat /Mono

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    Your humor is always welcomed here Tony.
    Nortavlag Bulc

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