Tuesday, January 24, 2012

Bulwark doors

Both the fore deck of my trawler and the aft deck are surrounded by a 36" tall bulwark, and to get on board the boat, and move from the pilot house to the fore deck, I had to create doors to pass through the bulwark.

If you look up the definition of bulwark you will find phrase's such as a wall like structure raised for the purpose of defense. Basically, the bulwark is a solid steel fence surrounding the boat. Most boats use a handrail type system of stanchions and rails ( either pipe or wire for the rails). I like the solid bulwark, and although heavy, it adds a huge level of security to life on deck. On the fore deck, I added a 1 1/2" stainless steel pipe handrail to the top of the bulwark, giving me a finished height of about 44"... pretty comfortable height. I've yet to add a hand rail to the aft deck as I am worried about interfering with the view as the aft deck will be the sun downer lounge.

The aft deck has two doors to use to gain access to the boat depending on how she is moored. The choice to get on board will either be by using the swim platform, and up the three steps to the deck, or using steps on the dock, the through the bulwark on the starboard side.

The wheel house is protected from the fore deck by another type of bulwark called a Portuguese Bridge. This is basically the same as the deck bulwarks, but much taller @ 46". The Portuguese Bridge will allow one to leave the wheel house while at sea with a greater sense of security. The Portuguese bridge also adds a huge level of protection to the wheel house in rougher times when green water might be getting to the fore deck. To get from the wheel house to the fore deck, you have to pass through the third door I had to fabricate.

The bulwarks and the Portuguese bridge are one of the architectural details to this boat that makes the boat more blue water capable.

The doors are hinged by a simple 1/2" stainless steel pins that have the door sliding over the pin. To make the hinges, I welded heavy walled tube to a tab, then fit the 1/2" pin to the tube. To avoid having to turn the pins, and bore the tubes, I used material with the same outside diameter and inside diameter. Since the pins and tubes are the same ID and OD, I knurled the pin at the pin/tube interface to create an interference fit between the pin and the tube. I removed a few thousandths of the pin on the door side while I had them in the lathe for a smooth action of the door on the hinge. The pins can be removed with a punch and hammer. While I was in the hinge making mode, I decide to make and extra set of pins for all the doors and add them to the spare parts inventory for the boat.

I wanted a simple, robust way to latch the doors closed, so I decided to fabricate a dogs for the doors. To make the door dog, I used 3/4" stainless rod, and rounded over the ends on the lathe using a round over bit. I then bored a 1/2" hole through the handle. On the door side of the dog, I used some 5/8" stainless round stock, and turned about an 1 1/4" of the stock down to 1/2". I then used the lathe to cut threads on the now 1/2" piece to fit 13 TPI nuts. I'm using nyloc nuts so that the action of the handle will not loosen the nut as the handle is turned. All the doors will land against a wooden jamb that I will bolt the the bulwark frame, then the door dog will be turned against a stainless steel wear plate screwed to the wooden jamb to lock the doors down fast. I might add a gasket between the door and the jamb to help help with keeping paint on the door edge.

The doors are painted the green color of the hull on the outside and the off white color of the bulwark on the inside. The green paint went on the doors great, but I had some problems with the white paint. For some reason the white did not want to atomize, and I found myself with my first paint problem. I tried some reducer in the paint, but that make the paint to thin, and it would not stay vertical so I got some sags. My paint supplier is helping me work this problem out, and once I get a handle on the problem, I'll finish painting the doors and post some installed pictures.

I've tried to repaint the white on the doors by tweaking a few things with not much luck. One thing I have discovered is that the acrylic urethane paint I'm using is extremely tough. Because I'm unhappy with the finish of the white, I've had to sand the poor finish back down to provide a smooth substrate for the next coat of paint. This is the first time I've ever had to sand this paint, and given what I've experienced, I can promise all of you who are reading is that this paint will have excellent abrasion and toughness, and will give me years and years of service.