Commander #155 'Mephisto Cat'

[Rico]

I am slowly catching-up on posting the many little projects that I've undertaken. Here is one more:

I have noticed that some boats come with Spreader brackets that are made out of aluminum, or some sort of alloy.

My mast came with nicely stout Stainless Steel spreader brackets. I found it odd that there was no compression pipe spanning the gap inside the mast, but it is most likely that the design did not require these.

Pearson did build these little boats with a proportionally large mast that has a very strong section... I do not think that Alberg's drawings, or Pearson's production design included compression pipes in our masts, but I thought it prudent to install these as an upgrade...

The Spreader brackets are fastened by 2 bolts that go right through the mast. The lower bolt also secures the upper end plates of the forward & Stern lower stays. The role of these fasteners is not an unimportant one, so one would like these to be stoutly in place, but tightening excessively will weaken the mast at the mid-point (where the spreaders are located).
The idea behid the compression pipe is that this pipe will act as a strut and take the compression load that comes from tightening the bolts at the spreader brackets relieving the mast from this pressure & avoiding the risk of weakening the mast ...

The installation is quite easy. The hardest part is perhaps finding the correctly sized pipe, as your average hardware store does not carry stainless steel pipe - you'll need to look at a rig shop, or industrial supply shop.

- I went with stainless to match the material of the bolts that will go inside the pipe. I was lucky to find a 14" or so scrap piece in the stainless scrap pile which I got without charge from a friendly rigging shop. - If well isolated, I suppose aluminum pipe will work... but you have to take care to use plenty lanocote to isolate the different metals.

Picture #1
The pipe that tightly fit my fasteners came with an 0.75" OD (outside diameter) which gave me a nice thick pipe-wall as pictured. Pipe is sold by specification of the inside & outside Diameter.

I had a machine shop cut the pipe for me as it is important to have paralell cuts at the ends. I made the cut marks a bit generous as I needed a close fit. (Cannot make the pipe longer after it is cut!!) I used a grinder to fine-tune the length, and to achieve the appropriate bearing radius at each end.


Picture #2
It is important that the inside diameter of the pipe matches your fastener's diameter closely, the outside diameter dimension can vary more as long as you get a nice stout pipe... but not too big... I'd say the size pictured is about as big as you'd want to go... Half that thickness would be strong enough... Note that the pipe-end in this picture remains flat as I had not curved the end to match the mast extrusion curvature.

After painting the mast, I covered the base of the brackets with several layers of vinyl tape to avoid scratching the painted surface and to isolate the Aluminum from the stainless. I then cut the pipe to the appropriate length and added a curve to the ends to match the mast's profile.

I drilled the hole in the mast that is just big enough to insert the 0.75" pipe into the mast. Enlarging a hole can be tricky - you do not want to 'move' the hole - just enlarge it. I used one of those sheetmetal drill bits that have a number of stepped diameters and I found it to be the ideal tool to do this as it keeps you well centered when using a drill motor by hand.

Picture #3
You can see the old hole and a new hole with the pipe & bolt in it. (I did them both the same way) -It is hard to see, but the pipe end now matches the outside curve of the mast. See folowing post for a close-up of this.

(I used red paint to cover-up the bare aluminum as all the white paint I had was two-part - I did not loose any fingers on this project, I am happy to say!)

Picture #4
This is essentially how the whole thing fits together... (I took this picture at the time of testing for pipe length and you might notice that the end of the pipe is still flat at this point.) When complete, the pipe only extends out of the mast by only a bit and matched the mast's profile curve.