For the very latest activity, click here: From a Bare Hull

Friday, September 25, 2009

You Can't Always Get What You Want


A number of readers have commented on the bow pulpit posts about accommodating some of the newer anchors like the NZL made Rocna anchor. These anchors, with their "roll bar" appear to be the "superior" anchor of the day (if not most expensive, they are still under patent I presume). Problem is fitting them to a larger platform style pulpit/bowsprit like that of the Westsail 42. The "roll bar" feature of these anchors creates difficulty in that the roll bar will collide with the underside of the platform as the anchor is pulled up and stowed. At this time, the best thing we can do to handle this is designing an option to "drop" the forward roller so the anchor effectively stows underneath the platform. This has the advantage in that it will cause the anchor to be self-launching, but the shank of the anchor might have "stick out" a bit above the platform.

Another way is to do a "third" small roller way forward so that the anchor's rollbar can clear the very forward of the pulpit. I have seen this on a couple of boats down at the marina, albeit on smaller pulpits.

On another note, after looking at pulpits on other similar sized boats down at the marina, I think we will stick with 2.5" tubing for the perimeter frame of the platform. We were considering 2" as that was the largest my stainless guy could bend, but I think this would be an area we don't want to skimp on as it relates directly to strength. So I need to find someone else who can at least bend this size tubing.

Wednesday, September 16, 2009

Playing With Software

Been playing with Maretron's N2KBuilder program. It is a software package that aids in the design of NMEA2000 networks for boats. Somewhat like a CAD program, you can place N2K devices on the drawing and connect them with cables. The software will tell you if and where there are problems with things like connections, cable lengths and voltages. All before a single piece of hardware is installed. The cool thing about some NMEA2000 manufacturers is that they not only cover "typical" marine electronics like GPS, depth sounders, etc, but there are also manufacturers of devices like tank level monitors, engine monitors, etc. The type of device that could be connected is almost limitless. N2KBuilder is only in version 1.0 and it lacks some handy features (like multi-select). It will be interesting to see how it evolves. Of course our project is nowhere near the marine electronics stage, but, by the time it is, the NMEA2000 market place should be fairly evolved with lots of interesting devices.

Sunday, September 13, 2009

All Chainplates are In!

And they ain't coming out! All the boat needs now is a couple of sticks tied to the plates, with white sheets hanging off them, and she's ready to sail! The shiny stainless steel shows off how bad the 30 year oxidized gelcoat hull needs a paint job. One thing at a time I guess. The chainplates were bedded/sealed to the exterior using Sikaflex 521-UV, and the nuts and washers in the interior for the bolts were liberally gooped with 3m 5200. There should be NO leaks and those nuts should not come loose unless forced. Positioning the chainplates according to the designer's drawing went fine. Although a couple of plates had to be moved a couple inches to avoid collisions with a bulkhead. These were not the primary plates (forward lower shrouds) and I was assured by the designer that a couple of inches won't make much difference in the rig. The star tools for this project were razor blade paint scrapers and dental picks for trimming/cleaning the cured Sikaflex from around the chainplates. Now, with the chainplates installed, interior work can continue knowing where these things are and how to hide, yet preserve access to them.
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Friday, September 11, 2009

See What I Mean?

Stare at a drawing too long and you start worrying about details. This is a test fit of a 45lb CQR on the bow pulpit, side view. The design has now moved beyond angle iron for roller slots to custom cheek plates with holes for the anchor roller axles placed specific for various style anchors. Fitted so far: Delta and CQR. Need to do at least a Bruce/Claw as well.

Saturday, September 05, 2009

Revisiting the Bow Pulpit Design (again)


Not sure what it is. Seems the more you stare at a CAD drawing, the more you want to change it. I wonder if design engineers have this problem.

Well, one of this fall/winter's big projects will be the bow pulpit. Factory finished Westsail 42's had two style bow pulpits. Early production boats had their pulpit hinge bolted to flat plate brackets surface mounted to the hull, just underneath the caprail. Later production boats had the mountings thru-bolted to the top of the caprail. In both cases the pulpits were fabricated from 1 inch tubing for the upper rails, 2 inch schedule 40 pipe as the perimeter structure, and 1.5 inch angle iron for cross members. All stainless steel.

Between the two original designs, I prefer the second model as it produces a platform that is more flush with the top of the caprail. The anchor chain does not have to go "up and over" the caprail. With the second design, it can go "up" to the bow roller. Therefore, my latest design iterations have started with this second model. Of course, I want to make changes, which are listed as
  • integral rubstrake for the anchor chain
  • place to mount chain stoppers
  • any small tweak that might improve strength
  • single person/wrench ability to install/remove
I do have a copy the original 30 year old drawing of the "revision 2" pulpit sent to me by Bud over at World Cruiser, so I started a CAD drawing based on that. "Feature" changes to that drawing include
  • four attachment points, instead of three
  • forward attachment points act as rubstrakes for the anchor chain. Also can have chain stoppers mounted
  • use of fiberglass grating instead of teak planking.
So, after showing the factory original drawing to my stainless fabricator, we came to the conclusion that the reason for using angle iron and schedule 40 pipe was likely due to the fact that it was the more readily available material of the time. Nowadays, stainless tubing is easily available in various sizes, pre-polished in 600 and 800 grits in both 316 and 304 grades. So, with that, the drawing has been updated to use 2 inch and 1 1/4 inch tubing (instead of the schedule 40 pipe and angle iron) with comparable wall thickness. Furthermore, round tubing for cross members in such a structure will give more strength over angle-iron and may be cheaper to use (comes pre-polished and requires fewer welds).

Finally, we have a tentative plan on how to proceed. The pulpit build will happen in three phases:
  • The first phase will be fabricating just the "platform" with no "upper rails" and no mounting tabs, just the basic tubing structure. Then it will be test fitted to the bow of the boat so the size and positions of the mounting tabs can be dialed in. The fiberglass grate for the top of the platform will also be cut and test fitted to determine where the grate mounting tabs should be placed.
  • The second phase will see the pulpit mounting tabs, the mounting tab backing plates, and the forestay/bobstay plate fabricated (all probably jet-cut), then welded to the platform. It will be taken back to the boat for a test fitting/mounting. Backing plates will be set and the platform will be thru-bolted.
  • Finally, if everything matches and fits ok, the platform will be removed to have the upper rail tubing fabricated and welded. The pulpit should then be ready for final installation.
Piece of cake, as they say. As for timetables, maybe by spring time next year we will have a bow pulpit installed. Of course, I reserve the right to change my mind at any time!

As for the stern pulpit, that should not nearly be as complicated.


Click here to see a more detail drawing of the bow pulpit platform.