Shellback Dinghy Rail

Hello

I am in the process of building a Shellback. I have built the hull and turned right side up. The design shows a 1-1/4" x 5/8" solid guard rail along the outside top of sheerstrake with a 7/8" x 1/2" inwale with spacer blocks on inside of sheerstrake.
I am thinking of changing the outside rail to be attached to sheerstrake with 1/2" spacer blocks with 2" gap between blocks and having solid rail as inwale attached directly to the sheerstrake. I thought that I could then thread a spiral 1/2" rope along the outside rail.

I thought this would act as a bumper strip in lieu of a plastic/rubber gunwale guard that required to be tacked or screwed on. Also thought it would look better and act as a tie down point for a cover if required. I would appreciate any learned comments on whether this is practical or not.

Thanks
Kevin

Rope rub rails once was fairly common, but they don't last very long, in terms of durability and looks. In the looks department, they tend to move around, depending on attachment method (traditionally they were fastened over a bedding) and they discolor quickly from UV and abrasion. If they are fastened over bedding, they can be removed and replaced as needed. If they are glued, it's a lot more work to R&R them, but still can be done if you're careful. In either case, the best way is to plow out a shallow groove, with about the same diameter groove as the line, usually about 1/4 to 1/3 as deep as the line diameter. This helps keep the rope aligned (the groove resists sagging, movement etc.). A square (flat bottomed) groove also works, but not as well and requires a lot more bedding.

This is why many have moved to other rub rail approaches such as rubber hose, banding, metal and plastic strips, etc. These generally tend to be tougher, tolerate UV longer, stay aligned (non-sagging), etc. Rubber hose works and is installed the same way, but it can also leave marks on stuff you bump into. The same is true of some types of plastic or rubber strip. I prefer metal (half oval), as it's way tougher than plastics, natural fibers and rubber, but is more costly and sometimes difficult to apply on small craft, because of the "quick" curves used.

I'm not sure I understand your changes to the inwale, spacers and rub, but it doesn't sound like sufficient enough of a difference, make significant differences in longitudinal stiffness (the main purpose of a sheer clamp, spacer, inwale arrangement). It's an old engineering approuch and better, lighter arrangements are used in modern craft, but it's still a viable technique and some just like the look of a spaced out clamp, which also helps if you need to turn the boat on edge to drain off water, which is why canoes use this setup.

Post some photos, so we can see what you're envisioning.

Thanks PAR. Those points you made regarding rope rub rail make me aware that it is not such a good idea. Too set it up properly sounds more trouble than what its worth. I shall consider other products for the purpose. What did you refer to as banding?

Banding is commonly plastic or synthetic rubber products. They often are pushed into an extruded aluminum rail base groove. Just about every modern powerboat uses them and there's dozens of styles, some not half bad looking. I personally don't think any would look good on a ShellBack though. Everyone that I know that has tried the "rope trick" has replaced it with something else once they needed to.

The traditional options seen on these puppies are a tacked canvas cover over wood or some even a little padding (rubber).

http://www.ballentinesboatshop.com/i..._08_0813-2.jpg

A simply hardwood rail.

http://www.harrybryan.com/harrybryan....daisy12.6.jpg

http://www.classicboatshop.com/usa/w...-half-oval.jpg

A metal (brass in this case) half oval, which are available as a hollow or solid back. The hollow ones are a lot cheaper, but can dent if not backed up with something significant (wood usually). Solid backed are truly tough, but you pay for this.

The ShellBack is so light that a good quality (and selected) length of hardwood will do fine, as there's just not a lot of inertia involved when they bash into stuff, though mother nature and other boats might not be as kind to her, as she will be to herself.