Thread: 12ft Tunnel Build

  1. #221
    Team Member zul8tr's Avatar
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    Really looks great. Are some or all of those sponsors or just show decals?
    What is the pitch of the Ron Hill prop?
    What gear ratio is in your engine?
    What speed do you expect?
    " Three may keep a secret if two of them are dead" Ben Franklin

    Location: SW Orlando, Fl

  2. #222
    BoatRacingFacts VIP John Schubert T*A*R*T's Avatar
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    Your build & rigging is great, just one comment. You mentioned that the ends of the newly extended steering bar are aligned with the swivel pin of the clamp bracket. From the picture they look to be far forward of the swivel pin location, and if so, the steering won't work correctly.

  3. #223
    Team Member ice_spy's Avatar
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    Zul8tr it's a standard tohatsu MD50 gearbox 1.85:1 The cowl and bed pan has been swapped with a 40hp merc for damage reasons, the Hillmarine signature race clever is an 18p to begin with, not intended to provide maximum speeds yet.
    Stickers are for show, from some of the products and companies I use, some I've just collected over the years. They also do a good job of covering up paint defects and runs
    I'm expecting speeds over 60mph to begin with.

    John, thank you. Believe me I spent hours today making certain that the bar ends are dead in line with the tilt tube. I placed a rod through the tilt tube and made exact measurements and insured alignment. What you are seeing in some of the pics is the motor turned fully to one side to show the distance of the bar end away from the fuselage. I will take a picture from above with the bar in the tube again, which will give better representation of its alignments
    The race never stops

  4. #224
    Team Member ice_spy's Avatar
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    Here's a quick drawn on pic showing it's alignment. The angle of the photo does not represent the alignments properly. pictures can be deceptive, just like in this pick the nose cone on the gear case appears to be in a higher position than the prop shaft when in fact the point is slightly lower.

    I do have a silly question as I have never set up outrigger steering with exact tilt tube alignment before... can you tilt the motor when it is in a turned position ? Does this effect cable tension ? Or should you only tilt the motor when you are going straight ?
    The race never stops

  5. #225
    BoatRacingFacts VIP John Schubert T*A*R*T's Avatar
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    We are talking about 2 different things. First, you need to align the ends of the steering bar with the swivel pin not tilt pin. The swivel pin is the vertical pin that attaches the drive shaft housing that swivels left & right (for steering) to the swivel bracket. The tilt pin is what attaches the right & left side clamps to the swivel bracket to accommodate allowing tilting out & under, & BTW with cables tight it will still permit trimming "in" & "out". If the steering cable ends are not in line with the swivel pin, as they aren't now on your set up, the steering will not work correctly. Will lock up one way & loosen the other.

  6. #226
    Team Member zul8tr's Avatar
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    [QUOTE=ice_spy;146112]Zul8tr it's a standard tohatsu MD50 gearbox 1.85:1 The cowl and bed pan has been swapped with a 40hp merc for damage reasons, the Hillmarine signature race clever is an 18p to begin with, not intended to provide maximum speeds yet.
    Stickers are for show, from some of the products and companies I use, some I've just collected over the years. They also do a good job of covering up paint defects and runs
    I'm expecting speeds over 60mph to begin with.

    For speed at 60 with that pitch and gear ratio you need to turn about 7000 rpm with 7 % slip (zero slip not possible) at the prop, definitely doable speed. I suppose you will run over 7000? Not familiar what that Merc will rev to.
    John is right where the steering bar end holes need to be relative to the engine left - right pivot.
    " Three may keep a secret if two of them are dead" Ben Franklin

    Location: SW Orlando, Fl

  7. #227
    Team Member ice_spy's Avatar
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    Ok, now I understand what you are saying. I didn't pick up on the swivel tube term sorry , i misinterpreted for the tilt tube. I was under the impression it had to be aligned with the tilt tube so that when tilted up or down tension does not change due to an arc if it were not in line with the tube. I see what you are saying, It makes sense that the steering pivot point is the swivel tube. And then where I must of been mislead, is the bar end hieght is meant to be the same as the tilt tube in line with hieght not in line horizontal across the boat ?
    Feeling a bit confused. At least I can simply cut some off the bar ends if needed. Appreciate you picking up on that thanks John.

  8. #228
    Team Member ice_spy's Avatar
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    Ok, so the plans have misled me to believe I needed to place in line with the tilt tube, also from a small 9 ft hydro I had it was in line with the swival tube but tension on tilting was affected. I see this set up allows pivot from the swival tube and keep tension at the tilt tube with this extra extension on the bar ends before the pulleys.
    The race never stops

  9. #229
    Team Member Chairman's Avatar
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    I disagree with the above opinions, and say that you have set it up correctly -- aligned with the TILT pivot point. Otherwise, your will cables will either tighten or loosen as you run your trim, and the differences in cable tension can be considerable. If you set your cable tension with the motor trimmed all the way down, the cables will tighten as you trim up, possibly to the point where something is liable to break.

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  10. #230
    BoatRacingFacts VIP John Schubert T*A*R*T's Avatar
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    Not true Chairman, they must be aligned in a line that the ends of the steering bar are even with the swivel pin, it's physics. I've rigged so many boats I can remember the number. If not aligned the cables can tighten or loosen when steering. Now the issue of trimming & the cables, sure they will tighten some when trimmed down & loosen some when trimmed up, but shouldn't break the cables. We never did when I drove for OMC.

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