Trailer Bunk Positioning

[SantaCruzin]

I finally tracked down a trailer for my 1968 West Wight Potter 14 and I'm hoping to get a gut check on how I set up the trailer.

Previously, the boat was on a trailer which had 2 keel rollers (one at the front of the trailer about 4' back from the bow stop and one at the rearmost crossmember, which ended up about 2' forward of the transom) and 2 basic swivel bunks (2x4 on edge, about 2' long). To my eye, the bunks slightly deformed the bottom of the hull so I wanted more support.

The new trailer has 3 keel rollers (two in the same positions as above, one right in the middle of the centerboard trunk) and two 4' bunks. The bunks are 2x4 but not on edge. The vast majority of the weight is on the 3 keel rollers, I can almost move (swivel) the bunks slightly there is so little weight on them. My understanding in the past was that bunks were mostly there for support, but the keel rollers should support most of the weight. Is that the case?

 

[Tedd]

I'm not very familiar with the WWP 14 so take everything I say with a grain of salt. These are just some generic thoughts based on setting up a couple of trailers for boats I've owned. I'm assuming that your WWP 14 has a retractable centerboard, as shown on sailboatdata.com.

Is it important that the boat roll on and off the trailer? If it is, then I'd be tempted to get some beam roller assemblies--probably four of them.

If the boat will float on and off, then all you need for "keel rollers" is something to keep the bow, forward hull area, and keel from whacking into anything on the way on and off. Pads and bunks are better in the float-on/float-off case because they spread the load out more.

Here's how the pads, bunks, and rollers are laid out on my boat, which is much bigger and heavier than a WWP 14.

• The main support is four pads (fore and aft port and fore and aft starboard) under the area where the hull ballast is located.
• Outboard of those four pads and toward the stern are two bunks (one each side) whose purpose is to stop the boat from rocking laterally. (The four pads are only about two feet apart, so additional lateral support is needed.)
• Under the bow are two pads in a V that stop the boat from pitching forward.
• Under the stern are two pads in a shallow V that stop the boat from pitching aft.
• There are also two pads on each side, at about waterline height, that act as guides while floating on and off and also help keep the boat centered on the pads.
• There is one roller on the centerline, just aft of the bow pads, whose purpose is to prevent the bow from hitting the trailer frame while floating on and off.

 

[SantaCruzin]

Thank you very much, Tedd!

I do indeed have a retractable centerboard.

The boat floats on and off in 95% of situations. I added the keel rollers as I've had bad luck in the past with simple pads on the trailer cross members. They're soft enough not to damage anything majorly, but I have had them cause an issue in one shallow retrieval situation where it scuffed the hull quite a bit. The keel roller, to me, serves essentially the same purpose but the fact that they roll should an impact with the hull occur gives me some peace of mind.

I forgot to mention that there is also a large V pad at the bow stop.

So it sounds like, at least in your experience, my understanding that a bunk provides lateral support rather than weight-bearing support is accurate? I know my boat only weighs about 600 lbs, but I'd rather be safe than sorry.

 

[Tedd]

So it sounds like, at least in your experience, my understanding that a bunk provides lateral support rather than weight-bearing support is accurate?

I can’t say with any certainty what’s common but that’s how it is on my trailer. I’ve seen powerboat trailers that only have bunks, so that can definitely be done. Sailboats are quite different from powerboats, of course. Much less near-horizontal area to work with for the weight of the boat.

My boat has lead ballast in the hull so it makes sense for the main supports to be in the same area as the ballast. I think your situation is different. You may be able to use a set up more like a powerboat. But, as you say, caution is wise. It’s easy to add more support and you’re unlikely to regret it!

A friend of mine has a very large boat (Imexus 28) supported entirely on beam-balance rollers. He says it’s amazing. He has a lot of rollers, though. About 48, I think.