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Old 29 October 2009, 13:37   #21
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Country: New Zealand
Town: Tauranga
Boat name: Extra Pleasure
Make: Atomix
Length: 5m +
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Yeah I don't like anything which the 'possibility' of arch damage... not worth the risk!!! living on the edge a bit too much i think...

although taking bridle up from eye, and just lopping around base of arch might work as it'll just raise it up a little, and by going right around the bottom of the arch will be at it strongest point...

It's anchored with 4 screws in 4 legs (2 either side, back and front), so 16 screws in total... so it's pretty well grounded...

See my professional diagram attached... so although the bridle rope is going around the nav arch, it is right at the bottom, (rather than using a rope from the top of the arch, at its weakest point) and also it'll just be rolling around it - most of the force will still be taken by the transom eyes...

Looks like I need another biscuitting session to sort it!!
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Old 30 October 2009, 06:27   #22
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Country: UK - Scotland
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What are you attatching the bridle to? I guess as it is a designed tow / trailer anchor it might be thru- bolted. Can then fix it inboard and the force on the frame will be reduced to a mostly inward pull (Vectored forces) which will be mostly perpendicular to the screws and slightly forward, so they will be mostly in shear and the plate being forced against the transom. Your sketch will effectively double the force the frame has to anchor - that arrangement will turn your bridle into a 2:1 pulley system!

I'd stick with replacing the nut / bolt on the inside of the current tow eye with an Eye version, then loop it as described earlier. That means the frame will only be taking the force resulting in the direction change of the rope rather than twice the tail load.
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Old 30 October 2009, 12:48   #23
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Country: New Zealand
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Boat name: Extra Pleasure
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Length: 5m +
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Join Date: Aug 2009
Posts: 182
Quote:
Originally Posted by 9D280 View Post
What are you attatching the bridle to? I guess as it is a designed tow / trailer anchor it might be thru- bolted. Can then fix it inboard and the force on the frame will be reduced to a mostly inward pull (Vectored forces) which will be mostly perpendicular to the screws and slightly forward, so they will be mostly in shear and the plate being forced against the transom. Your sketch will effectively double the force the frame has to anchor - that arrangement will turn your bridle into a 2:1 pulley system!

I'd stick with replacing the nut / bolt on the inside of the current tow eye with an Eye version, then loop it as described earlier. That means the frame will only be taking the force resulting in the direction change of the rope rather than twice the tail load.
oh!


thanks for the heads up... i forgot all my highschool physics as soon as I walked out the classrooom!
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