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Modifications and New Ideas

We have made some changes over the last year in an effort to improve the NN10 and make it easier to build. Some changes were suggestions from buyers and some were undertaken to solve issues we noticed with our own NN10. Some were continuations of ideas passed on to us by Barry Niccolls as he attempted to unload the more than 10 years of development and building experience he has had with this fine little vessel.

We will be offering upgrade kits for some of these changes so current owners can add the improvements to their dinghy.

The following is in more or less chronological order as we implemented the changes.

Boom end fittings and two piece boom:  Aft end plug machined from acetal, also known as POM (polyoxymethylene) or Delrin, with an integral fairlead for the main outhaul line.  Shipping a dinghy to the UK just before Christmas required crating the NN10 to minimize the volume and reduce the airfreight cost.  The 86 inch boom (with fittings) is the longest item of the disassembled dinghy with sail option so cutting it into two pieces also makes it easier to stow with the mast sections.  As with the mast sections I cut the boom on a 45 degree angle so that when assembled it preserves the relationship of the fittings, top and bottom end to end.

Not finding a pvc tube of the right diameter, we used the same 1-1/2 inch diameter acetal rod used for the boom end plugs, turned down for a tight fit and fastened into the forward short section of boom with marine adhesive/sealant.  I placed the cut just forward of the forward mainsheet mini block.  It seemed structurally better to keep the boom unbroken between the two mainsheet mini blocks so the aft section of the boom is longer than the forward section. I also found I had to drill a small pressure equalization hole through the aft boom end plug. The seal between the aluminum tube and the machined acetal rod connector was tight enough that the air trapped inside made it harder to push the sections together and take them apart.  I had visions of the boom pushing itself apart as the sun heated it while out sailing! Or having it explosively propel the end of the boom out into the water from the dock after taking the restraint of the main outhaul line off after being out in the sun! I’m not sure what the penalty might be for shooting someone with such a projectile but better avoided.

The forward end is also now machined from acetal and went through two versions, one with a 3/4 inch hole through for the existing boom fork or gooseneck which was a re-purposed plastic oarlock. This oarlock seems to have changed plastic formulations from previous years and has recently suffered several catastrophic failures, particularly in the colder months this last winter of 2009/10. These failures led to the second version of the plug which now has a 1/4 inch hole and led to the complete redesign of the boom gooseneck and mast fitting detailed below.

Lower connector fittings in bow section:  The large plastic screw connectors are an elegant solution to the problem of connecting the two sections of the dinghy.  As they are another re-purposed off-the-shelf fitting intended as a bulkhead adapter for fuel tanks, there are some issues! Number one is the frustration of every first time owner when I have forgotten to explain that the threads are reversed, as is required for fuel fittings (like your propane tank fitting for your BBQ).  I think this is a bit of a bonus, like a secret handshake which immediately identifies NN10 owners.

The next is the 1 inch NPT threaded hole through the centre of the connector.  In the bottom two connectors particularly which are at or below the waterline when the boat is in the water. Problem; how to keep water from flooding in through the connector holes in the bow section bulkhead and filling the well between that bulkhead and the mast step seat.  Very annoying to have to bail out after connecting the sections. In looking for something to hold the connectors in the opening to limit the amount of water entering while doing the connection I decided to try machining another of the plastic nuts supplied with each connector to project through the bulkhead to be flush on the aft side. They are then fastened with marine sealant/adhesive and secured with six stainless screws exactly as the upper connector nuts are.  Then we had some plugs machined from black acetal rod and threaded to screw into the centre hole of the connector, one from each end and sealed with the same marine sealant/adhesive.  Bonus for this is that the air chamber created provides additional flotation. We designed some nifty round white logo buttons to fit into the centre of the connectors on top of the plug and make them more visible if accidentally dropped in the water.

Boom gooseneck and mast fitting:  The plastic oarlock/boom fork is gone!  Whatever has recently happened to the plastic formulation of this off-the-shelf fitting, we had two customers report failures of these parts this year and I was able to replicate the failure several times and very easily. The failure happens when the oarlock fork is snapped over the mast fitting, a repurposed/machined PVC adapter which one customer descriptivelly calls the “wagonwheel”.  The arms of the oarlock shatter into several pieces.  It has also happened by merely dropping the end of the boom from waist height to a dock. We now have shipped the first upgraded gooseneck fitting which is made of 0.065 wall 304 stainless steel and white Boatboard, the extremely tough HDPE product we use for outboard mounts on the transom, rudder cheeks and daggerboard top. I will put a picture of it here as soon as I get more made. The bonus to being more rugged is that it is more compact on the mast, allowing the mast sections to stow more easily, although now we may have to redesign the stowage bag to separate the mast and boom sections in individual pockets to prevent the stainless fitting from chewing up the powdercoat on the other sections.

Outboard pads on the transom:  When mounting a small outboard on our own NN10, I noticed that tightening the outboard clamps was actually compressing the transom lip slightly.  I am not sure how various brands of outboard differ in the clearance over the transom lip afforded by the clamping system but the fix for ours was to increase the thickness of the boatboard pad on the outside of the transom from 1/2 inch to 3/4 inch.  At the same time, I reduced the thickness of the inside pad from 1/2 inch to 3/8 inch which follows the slight curve of the inside liner more easily while still giving lots of abrasion protection to the fibreglass transom.  Bonus was that the 3/4 inch pad on the back makes it easier to bury the #10 nylock nuts in the Boatboard while leaving enough meat to take the pull on the machine screws as they are drawn up tight. It makes countersinking depth a lot less critical too which is good for reducing my stress level when doing the installation.  The overall increase in thickness is therefore only 1/8 inch but it puts an additional 1/4 inch at the back to make sure that the outside pad sits proud of the transom edge to insure that the outboard clamps cannot crush the fibreglass.