Below is a series of articles from the Fleet 13 Website on rigging a bare tube carbon boom and spinnaker pole. This project involved rigging two booms at once for USA 7346 and USA 7611. Note that this project was done just as the double spinnaker pole system was gaining popularity, but we, unfortunately, opted to rig these booms with the conventional single pole system.
Last night I started rigging 2 new booms for 7346 and 7611. Both will be set up with the conventional single port-side pole. They will be rigged with the option to go to double pole after the worlds this summer. That way we can source the proper parts and see all the fancy double pole setups that others have been refining this year. For now, we will be using what we are familiar with as worlds is only one month away!
Boom Sections – Windrush Yachts, AUS
Spinnaker Pole Sections – Unknown builder, sourced through Holger Jess
I was at a loss as to where to start, so I decided to work on the spinnaker poles first. My first step was to fit both end fittings to the tube. We got some really nice(although now may become obsolete) fork fittings from Holger. They are a really well made with a machined base and a heavy gage fork that can easily be pinched to fit all line sizes. These are far superior to the fittings made by Mark Angliss.
The forks were supposed to match the ID of the poles that Holger also provided but the metal sections that fit inside the tube needed to be ground slightly with a bench grinder/file.
The standard Spiro inboard end fitting is a smaller OD than the ID of the new carbon tubes. I sourced some delrin tube from McMaster with an ID that was the same as the OD of the ball end fitting.
The OD of the delrin tubing was oversized but was easily machined down to the proper size on the lathe. This material is very easy to machine. Should be fun to make some custom end fittings for the double pole system later this year…
The result is a very snug tolerance fit for the inboard end.
Gooseneck fittings, aft mainsheet lead, outhaul sheaves:
The boom came the proper length which meant there were no scrap pieces to use for molding backing plates or to use for reinforcing. I made a mold out of foam to help mold the gooseneck fittings. This was made by hot gluing sheets of foam insulation together to make a block and then sanding it using the outside of the boom and sandpaper.
The outhaul fittings provided from Windrush would have put the top of the boom below the boom band and required moving the gooseneck. I also did not like the idea of installing a goosneck fitting with fasteners. I first made a small riser pad using epoxy and 1/4″ chopped glass and some colloidal silica. I also used some black pigment for cosmetic purposes.
The idea I came up with was to use the supplied part and incorporate it into a bonded gooseneck fitting as Larry Tuttle and others have done. I liked the idea of using the stainless fitting so that the mating surfaces would be a metal/metal interface and would not wear over time.
The mold was lined with packing tape and sprayed with McLube. I wetted out 3 layers of 6 oz carbon and layed them up in the mold. Next, I set in the pre-fabbed risers along with more epoxy/chopped glass/filler/pigment mixture. I set the stainless fittings on a fid(sprayed with Mclube) that perfectly matched the ID. This way I could align the fittings on the center line of the mold even when I burred them in the epoxy mixture. At this point, I was not optimistic as the whole deal looked super ghetto-fied when it was all laid up.
The parts were un-molded the following day after 24 hours cure time.
Next, I trimmed the parts with a hacksaw.
I then began sanding the parts. This was more of an undertaking than it had to be due to my sloppy molding job. That said the parts tuned out far better than expected after they were sanded and fit to the inside of the tubes.
Gooseneck fitting inside the newly fabricated part. Note that this stainless liner will not “wollow out” as a composite receptacle will over time.
Fittings shown inside the boom sections. Note this is not super high end fit/finish, but they should be bomb-proof which is what I care about.
Fittings were then bonded in using the same mixture used to fabricate the parts. Tonight I will laminate a few layers of carbon cloth over the top of the fittings and onto the tube. I am very happy with how these turned out.
This fitting was also provided by Windrush. These will go on the aft end of the boom on the bottom to lead the aft mainsheet block. The block will be lashed around the top of the boom and then through this fitting to keep it from angling forward. Note that I am NOT tying the block directly through this fitting. It will be subject to shear and very minimal peel loading.
The areas were masked off and the bonding surfaces were then sanded.
Parts were bonded on with epoxy/silica/glass mix. Not that these parts were a hollow skin. the entire cavity was filled with the bonding mixture for strength and I will have to re-drill the hole after cure.
The first holes I put in the sections were the outhaul sheaves. Note that before I did anything I very carefully marked the top and bottom along the center line of the boom with masking tape. The booms have a thicker wall at the top and the bottom so it is important to get those types of details from the manufacturer before you cut anything. Also, note the hole has no sharp corners which have a higher stress intensification factor than curved corners.
Outhaul sheaves fit. These will be through bolted with machine screws/washed/nylon lock nuts. Cutting holes like this is far easier than in an aluminum section. I used a Dremel and a cutoff wheel to make a box and then sanded it to size with a small fine-grit abrasive wheel.
Stay tuned, more to come…
Installing more hardware, almost ready for line.
Detail showing aft mainsheet block installed. The hole in the bonded fitting had to be re-drilled and sanded smooth.
G10 mounting plate for the mainsheet block before bonding. The odd shape is to accommodate the Harken part so the block can pivot through the entire 180-degree range. A slight modification was also necessary to achieve this range.
The plates were sanded to the approximate profile of the boom. I masked the bonding areas and sanded the booms well for a good bond. They were bonded with West System 105/206 with 406 filler(colloidal silica) and a small bit of black polyester pigment.
This same epoxy/filler mixture was used to bond the outhaul cam cleat bases. Note that on these plates, I pre-drilled and tapped the holes. This way I could avoid adding holes to the underside of the boom near the vang fitting. I used some machine screws sprayed with Mclube to fill the tapped holes during bonding.
After I completed all the fillets on each G10 plate, I carefully removed the tape and wiped the surrounding area with acetone.
Outhaul cleat base on the underside of the boom near the front.
2 layers of 6 oz carbon were laid up over the top of the gooseneck fittings. Make sure you aggressively sand any bonding surfaces on the inside of the boom. There is likely still mold release/wax on the interior from when the boom was made.
The forward outhaul turning blocks were mounted and thru bolted using machine screws and nylon lock nuts.
The forward edge had to be sanded smooth after the layup had cured.
The G10 plates were re-masked sanded and spray painted black after they had cured. The hardware was then installed using Loctite blue.
For the mainsheet cleats, holes were drilled through the G10 plate and through the boom. Those holes were then tapped and fasteners were installed with Loctite. I talked with several people about putting these holes in the bottom of the boom. I wanted to avoid it if possible, but this ensures that the fitting will stay attached as it is not entirely relying on the bond. I used a hand drill to carefully drill these holes. In hindsight, I should have rigged up the drill press for this application to increase precision.
The vang strops were sewn using 1″ tubular webbing sourced from APS. I also spliced a 1/8″ spectra loop that was luggage tagged on the aft end of the strop to hook over the keeper fitting.
The keeper fitting was bonded on with a small loop (don’t worry, those holes are not drilled in the bottom of the boom!). This loop is used for the mainsheet shock cord, which is in place to keep things from hooking on the fitting.
The pole retraction thru deck sheaves were installed by drilling and tapping the boom. The fasteners were then installed using Loctite. I did not add any backing or reinforcement as these sheaves are very lightly loaded.
Next up is rigging the outhaul, pole retract, and the patented in-the-pole foreguy system.
Here are is a short video I took up at the harbor today. Very glad that that project is behind us and also very happy with the result. Many thanks to Samson and Harken, as always, for making this project affordable for those of us that have limited resources(recent college grads). Thanks also for everyone who checked out our site. I hope this is a resource that will help you if you plan on rigging a new boom. Feel free to email or call me with any questions, I will do my best to help you out.
Outhaul Block Backing Plate
I originally rigged the booms without a backing plate on the outhaul block. After talking with several people about this, it was evident that a G10 backing plate is desirable to distribute the load and keep the block from ripping out.
To do this, I cut a rectangle piece of 1/4 inch G10 slightly larger than the size of the block’s cover plate. I drilled the through-holes on the drill press and then sanded the piece to the inside profile of the boom. I then sanded the tube in preparation for bonding. With the boom upside down, the piece was bonded in with fillets using epoxy and colloidal silica. I used some fasteners sprayed with Mclube to line the plate up with the existing holes. After the epoxy had cured I then cut the through hole using the existing hole in the section as a template. The fitting was then fastened using machine screws and nylon lock nuts. This fitting is now very strong.
I do not have a picture of the completed outhaul block, but I did quickly draw up a schematic of the internal rigging. One thing you will notice is that with this setup for the flattener, it puts a lot of added load on the outhaul block when engaged. A good amount of the leach/vang tension is transfered to the outhaul block when the flattener is pulled forward. This is one of the main reasons why I think a G10 plate is desireable.