Go Back   RIBnet Forums > RIB talk > RIBs & ribbing
Click Here to Login

Reply
 
Thread Tools Search this Thread
 
Old 29 October 2009, 17:37   #21
Member
 
Country: New Zealand
Town: Tauranga
Boat name: Extra Pleasure
Make: Atomix
Length: 5m +
Engine: Outboard 60HP 2Strke
Join Date: Aug 2009
Posts: 182
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!!
Attached Thumbnails
Click image for larger version

Name:	Untitled-1.jpg
Views:	189
Size:	9.7 KB
ID:	47233  
__________________
rjbathgate is offline   Reply With Quote
Old 30 October 2009, 10:27   #22
Member
 
Country: UK - Scotland
Boat name: Wildheart
Make: Humber/Delta Seasafe
Length: 5m +
Engine: Merc 60 Clamshell
MMSI: 235068449
Join Date: Apr 2007
Posts: 4,671
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.
__________________
9D280 is offline   Reply With Quote
Old 30 October 2009, 16:48   #23
Member
 
Country: New Zealand
Town: Tauranga
Boat name: Extra Pleasure
Make: Atomix
Length: 5m +
Engine: Outboard 60HP 2Strke
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!
__________________
rjbathgate is offline   Reply With Quote
Reply


Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off




All times are GMT. The time now is 03:54.


Powered by vBulletin® Version 3.8.8 Beta 1
Copyright ©2000 - 2024, vBulletin Solutions, Inc.