newboater asked:
I also would like to know how to set the bunks for the boat to rest on the trailer right thanks for all the help
What is the difference between a float on boat trailer and other trailers?
2 Responses
Leave a Comment
newboater asked:
I also would like to know how to set the bunks for the boat to rest on the trailer right thanks for all the help
April 19th, 2008 at 8:44 am
The trailer, or at least the cradle section has to be completely submerged so the vessel can float on to it.
Bunks should be set to take an even part of the weight along their full length and should never have square ends. They must press against chines and/or strakes and must not bear on unbraced hull skin sections. They should extend beyond the transom not finish before it so the strongest part of the boat takes the load. Wineglass displacement hulls are very difficult to spread the load, but are probably the main type of boat that needs a float on/off trailer.
The keel is going to take the biggest proportion of thew load, but should not have all of it. It is nearly impossible to have too many rollers, but every roller must bear on a part of the hull that has a bulkhead or major frame member behind it. A combination of as many keel rollers as can be fitted, as many guide rollers as will do anything meaningful and at least one long chine bunk each side (my trailers have three each side, two full length for a total of six) will do some way to supporting your hull safely.
Bunks spread the load wonderfully, but rollers can have such a small contact area that they can have over 100 times the normal floating loading on the hull. Rollers must never be used for competition boats, or foam or balsa core or lightly built ply boats for this reason - they will quickly damage these hulls beyond repair. Alloy too must be supported on multiple bunks - not rollers except for the keel (and there you should have one every foot or so) unless you like a pattern of dents in the hull.
Edit - When towing any outboards should always be fully tilted so the engine weight is furtherest forward in from the transom, thus much less stress on the transom, and rear hull contact points.
April 21st, 2008 at 5:06 pm
You kinda answered your own question there. The float on trailer will of course have the rails to secure the boat from going side to side. You just have to get any trailer that fits the size of your boat and its ready to go. The boat trailers also secure the boat from moving forward and back with built in loops on the back to strap the back end down. They also have a rail on the bottom that connects a brace from the outboard to the trailer for keeping it from shaking up and down going down the road.