CS 17, Mk 3 "Just in Time"

[Chick Ludwig]

Most of the weight should be on the keel on as many rollers as possible. The bunks should mainly be to  balance the sideways load. You'll need to center the weight of the boat closer to the axle than it would be with the boat as far forward as a powerboat would be. Either move the boat back on the trailer by moving the winch stand, or, if you can, move the axle forward. most modern trailers allow you to do this. Also, the bunks should span across as many frames and bulkheads as you can get so they don't push against an unsupported part of the hull. If you don't have adjustable height roller brackets already, they are a good investment. I got mine on E-bay.

 

Set the longitudinal position of the boat first. About 10% to 15% of the total weight of the boat and trailer should be on the tongue. I like to set my rollers as low as I can with the boat on the trailer, then "jack-up" the bunks just enough to take a bit of the load. A hydraulic auto jack under the bunk brackets, one at a time, is handy for this.

 

Here's more discussion about trailer support: http://messing-about.com/forums/topic/9703-trailer-support/?hl=%2Btrailer+%2Bsupport

[IsZataRock]

Thanks for the info and advice, Chick.

 

I'll be modifying my trailer to give better support along the keel.  With any luck I'll be able to configure a nice longitudinal plank shaped to fit the keel that should double as a walking surface.  Rollers only if I have to.  So far my boat is very easy to launch and recover.

 

And, of course, I'll get my zipper zipped up nice and tight before my next trip!

 

There should be a picture or two once I get it figured out and implemented.

 

Hal

[PAR]

Instead of a centerline plank for the keel to sit on, consider a PVC plank of the same dimensions. These are available in the trim and molding section of the big box stores. They're mch slippery than a hunk of PT, they're inert so can't rot and they're fairly flexible, so the boat lives on something that'll give a bit, if you're not on perfectly, or bouncing down the road. This stuff cuts and machine easily and can be bent with a heat gun, if desired.

[Designer]

One more thing to add to what Chic said; the bunks should not go to the stern or follow the hull more than a foot or two aft of the companionway bulkhead. The reason is that there is less deadrise amidships than there is at the stern. What this means is that when you roll the boat off of the trailer, aft positioned bunks will lift the keel off of the stern rollers as the boat is moving aft, increasing the friction, just when you want the boat to roll off smoothly.

 

If you sink the trailer to launch, it probably does not matter. I prefer to just get the tires wet and let the boat roll into the water rather than getting salt water into trailer lights, wiring, springs and bearings etc. not to mention rusting out the frame.