CONTINUOUSWAVE

[Moderator's note: a second topic on the repair of Unibond hulls has been moved to its own thread.]

Q1: is a trailer with just two bunks sufficient for a 1972 NAUSET 16?

Q2: would a trailer with bunks and keel rollers be the right configuration?

Q3: if just two bunks are sufficient for a 1972 NAUSET 16, can an existing floppy-roller trailer be converted to a two-bunk trailer by removal of the floppy rollers and installing two large-cross-section (4 x 6) dimensional lumber planks on the existing flat brackets? (Here I assume I can loosen the bolt below the flat plate and get the angle to follow the shape of the hull, as seen in Figure 1 below.)



BACKSTORY
I recently purchased a 1972 NAUSET 16 that came on an E-Z-LOADER trailer with [floppy] rollers. I would like to convert this trailer to a bunk trailer. I suspect one of the rollers is actually [the cause of] a puncture in the hull that needs repair.

I have read that Boston Whaler recommends a keel-roller set-up with bunks for stability, but then they moved away from that and more or less now recommend anything but [floppy] rollers.

If the E-Z-LOADER trailer is in good condition, you certainly can convert it to a keel roller trailer with bunks.

As for trying to reuse some mounting components from the floppy rollers, it may be simpler to just buy the appropriate bunk mounting brackets. For two bunks you will only need four mounting brackets, so the cost should not be excessive.

Using 4 x 6 lumber for the bunks for a relatively light 16-foot hull may be a bit excessive.

Having a multitude of keel rollers on which the entire weight of the hull is to be carried is not an absolute requirement. A mix of keel rollers and bunks is entirely suitable for supporting a Unibond hull.

On my own trailer (which is also an E-Z-LOADER from 1992 and whose galvanized steel is still in excellent shape), I use two pivoting bunk sets of two-bunks (for a total of four bunks) to support the aft half of the hull, while two sets of paired keel rollers support the keel in the forward half of the hull. The boat spends about 99-percent of its life sitting on that trailer, and there is no indication that any any harm has occurred.

The keel rollers are very useful for loading the boat onto the trailer on a sloping launch ramp, as they will be the first point of contact between the hull and the trailer as the boat is pulled up and onto the trailer.

Your particular E-Z-LOADER trailer has curved crossmembers on the trailer frame. You can still use keel rollers, but you will probably need to use one-piece mounting brackest.

The general goal in the rigging of the trailer is to carry the hull as low on the trailer as possible. There are two factors which will determine how low the hull can be situated:

• the clearance between the hull and the trailer fenders; if your trailer is wide enough, it may be possible for the entire hull to lie between the fenders, but otherwise the chine line of the hull should be above the fender tops by about 1-inch; and
• the distance the keel rollers can be positioned above the trailer crossmembers; in some cases the lower mounting bolts for the keel roller one-piece mounting brackets can go through the crossmember. See Figure 2 (below).

While using paired keel rollers for a 16-footer might be excessive, mounting two keel roller brackets back-to-back will actually simplify the installation.

Note above in Figure 2 that in some situations the lower mounting bolts may need to pass through the trailer crossmember. This occurs when a higher roller position is desired. In that instance the holes for those bolts must be located on the exact centerline of the vertical face of the crossmember in order to minimize loss of strength in the crossmember. Be sure to use a galvanizing spray-on compound to restore rust protection for the steel at the drilled hole, before installing the brackets.

Thank you for your input.

Regarding the trailer, I am going to move forward with your advice of getting proper brackets so I do not need to build up height with the lumber to clear the trailer. I would probably lean towards installing four bunks that more or less mimic the location of the four lines of rollers that are currently on the trailer.

Q4: are flat 2x4, flat 2x6 or 4x4 lumber suitable or recommended for the bunks?

Q5: should I use two sets of back-to-back keel rollers (four in total total), and place one pair on each the front two trailer cross members?

Oops--I just looked at the trailer and [what I thought was] the middle cross member is actually the axle. I figure it is not advised to rest the boat on the axle so I would only have one available keel roller location on the front cross member. This doesn’t seem like much surface area to distribute the weight.

Q6: will just one set of paired rollers on the front crossmember be enough?

LeftyCK wrote:Q4: are flat 2x4, flat 2x6 or 4x4 lumber suitable or recommended for the bunks?

Most trailer bunks that I have seen are more rectangular than square, and the larger surface is the surface that bears against the hull. Maybe a 2 x 6 is a useful size.

LeftyCK wrote:Q5: should I use two sets of back-to-back keel rollers (four in total total), and place one pair on each the front two trailer cross members?

Oops--I just looked at the trailer and [what I thought was] the middle cross member is actually the axle. I figure it is not advised to rest the boat on the axle so I would only have one available keel roller location on the front cross member. This doesn’t seem like much surface area to distribute the weight.

Yes, you certainly do not want any sort of support mechanism mounted to the axle. If the trailer goes over a bump, the axle could be driven upwards. If you have a fixed support mounted to the axle, it would be jammed into the hull, probably causing major damage.

LeftyCK wrote:Q6: will just one set of paired rollers on the front crossmember be enough [support for the bow]?

I think on a 16-foot hull having one set of paired keel rollers on the trailer crossmember in the general bow area will provide good support for the bow.

As seen in Figure 3 above, the mounting height of a keel roller can be raised higher if the lower mounting bolt position is changed to a hole in the trailer crossmember. The hole in the crossmember should be drilled exactly on the center of the vertical face of the crossmember to minimize any strength loss due to the hole.

Roller mounted closer to the bow may benefit from having a higher mounting position.

Also note this trailer crossmember is bent to form a lower center section. Using a one-piece keel-roller mounting bracket allows for a simple and sturdy mount of the bracket to the curved crossmember.