Mast Head fittings, Winch Pads, and Boom

Some work from last weekend...

Finished the mast head assembly. I made it out of 1/2" plate with a mount for the Sat Compass, Airmar weather station, and anchor light:

I also fabricated the parts for the boom, which is pretty straightforward. It is set up for heavy lifting. The hardware for the (loose footed) sail will be bolted on later:

Here are some nice all stainless trailer winches that I found online for about $50 each (!).

I will use these to handle the down rigger pole up-haul lines. They seem to be very well made:

Fabricating the winch pads took a lot of trial and error, but I think they will work fine. The bigger winch on the back of the mast will handle the boom lift. With a four to one tackle, this should be just about the right size for lifting big stuff. The smaller winch on the side of the mast is for the halyard.

Mast Update

Lots of progress on the mast, but not so much on the blog...
Will try to catch up here with a bunch of pictures.

First off are some pics of the radar platform, which ends up at about the 10 foot elevation on the mast.
We jigged this up inverted on the welding table, then welded it to the mast:

Next up was finishing the TIG work on the crows nest and welding it to the mast at the cross trees. I also added some substantial structure to the bottom of the crows nest. This structure also ties into the mast and the cross trees and creates a solid attachment point for the forward diagonal bracing from the wheelhouse roof. The support wires for the down rigger poles also tie in here. The structure is designed to transfer the loads from the paravane stabilizers into the mast and bracing structure at this intersection as well:

The main engine exhaust extends from the stub-out at the top of the engine room stack, up the front of the mast to the top, where it exits to the port side of the mast. This keeps the exhaust up high and well above the electronics and rigging. This should also keep the deck clean of any soot and be quieter underway. The hangers were a little tricky, but I think the eventual design ended up pretty good... strong, easy to adjust or remove if necessary, and allows for vertical expansion and contraction of the exhaust tubing as it heats and cools:

Now that most of the hot-work is done, I am starting to work on rigging, mounting brackets for antennas and electronics, and installing pull lines for all the internal wiring to all the different locations on the mast. I don't have many good pictures of the wire chase inside the mast, but I installed a 2" PVC wire conduit that runs the length of the mast and has holes in the right spots for everywhere that the wiring has to exit to the various antennas and electronic gadgets that will be mounted later. The PVC conduit is riveted about every foot or so (from the outside) to the wall of the mast pipe, This worked really well and was not as hard to install as I thought it might be. The conduit will keep all the wiring from banging around inside the mast and driving us crazy.

The last picture is of what I think will be our means of ascending up to the crows nest. Its a "manhole ladder" which is about 12" wide, strongly built, and very light. It would be attached to the deck, the wheelhouse roof, and the port side cross tree at the floor of the crows nest. I looked at using mast steps, rat lines, etc. but this just seems like a much more solid solution. It would also serve as a way to easily reach the top of the wheelhouse (which will be the "second floor" on the way up to the lookout platform). With our type of boat, I'm really not too concerned with the extra windage this solution would give us. I've seen this set up on a lot of fishing boats and like most fishing boat stuff, it's practical and works well. 

                                                

Speaking of fishing boats, here's some of the Bodega Bay Fleet from a recent visit. Their mast and down rigger/strut set up is very similar to what we will end up with for our aft mast and rigging, and you can see the inspiration for our design:

Joining the mast sections

Last weekend we put in a good day on the aft rig. The big accomplishment was joining the two sections of pipe for the mast. We used a backing strip and full penetration weld. The trickiest part of this operation was getting the two sections lined up perfectly and keeping them that way throughout the welding process. We used three heavy flat bars for this, along with a lot of checking for true as we went along. The end result looks great and is totally true and straight. Next was welding up the "cross trees" which (along with 1/2" plate gussets) form the foundation for the crows nest, and the attachment points for the fwd diagonal bracing pipes that transfer most of the load from the paravanes down to the anchor points on the wheelhouse roof. Again, lots of measuring and eyeballing here to make sure we get everything straight and true. At the last minute, I decided to have the outboard 4 feet of the cross trees flanged so they can be bolted in place. The overall length of the cross trees has to be almost 6 1/2 ft on each side in order to provide a cradle for the down rigger poles. If welded to the mast in all one piece, this would have made the mast really cumbersome to move around and work on, so I think it was the right call. In the last couple of pics the crows nest is rough fitted on to the mast. Next workday, we"ll be squaring it up to the mast and welding it in place.

I am starting to put together a parts list for the exhaust extension, which will take the main engine exhaust up the mast and have it exit clear of the sail and other rigging. Here's some of my "cocktail napkin engineering" on that concept:

The next round of work on the rig will also include finishing up the down riggers and support pole connections. We got a little head start on laying these out and the geometry and clearances all look good so far. In the orientation shown below, the fore and aft hinge plates would be welded to the side-shell of the hull- the main down rigger pole hinge just aft of the wheelhouse and the fwd support strut hinge just ahead of the wheelhouse. According to the measurement below, it looks like we'll be able to board through the side gate and the stbd wheelhouse door with plenty of head room when the poles are stowed in the up position.

Also, I've been looking for a source for nice pre-made heavy duty bolt on pipe collars/brackets(?) in stainless for standard sch 40/80 pipe. These would be handy for attaching some of the cross bracing structure on the rig, the exact location of which can't really be finalized until the mast and down riggers are actaully installed on the boat. I've seen them on Nordhaven rigs and other fancy trawlers spars. We could fabricate these if necessary, but its quite a bit of work to get them right for a structural application. If anyone has any leads on these, please let me know.

Quick update

Just a quick update with some pics from last week. We completed fabrication of the four stainless hinge bases that will be welded to the hull to attach the down rigger poles and the forward support struts for the poles. The base plates are 1/4" stainless so we had to tack them down to some heavier plate to keep them from warping during welding. I found some 3/4" steel rounds that worked well for this. The heat from welding made the side plates want to warp as well. I had to use some threaded rod and bolts to get the assembly straight and square. In the end these came out nice and true, and the hinges operate smoothly with the Teflon washers in place.  We also jigged up the crows nest and tacked the basic structure together. After the holidays, we'll weld up the mast sections and start assembling the mast, cross trees, crows nest, etc. down rigger pole fittings and pad eyes are also ready to be welded up.