Experiments with GFK

Cam turret, before Big day: My first work with glass fiber and resin. I used some coins to calibrate a digital scale I bought for the purpose. Up to 100g it seems to be accurate down to the gram, which is what I need (the precision really sucks beyong 1kg).

I rounded the edges of the box with sandpaper to make sure the glass fiber won't lift (it does around sharp bends). I cut out one sheet for the top, and one sheet for the sides.

Cam turret, after When mixing resin and hardener I was surprised the result is so liquid, and hardly smells at all. I used a foam roller to generously apply resin to the (rather thursty) wood. I put the glass fiber on, and added more resin with the roller. I had to cut the fiber cloth here and there to ensure a smooth fit, but it all worked pretty well. I used some leftover resin to fill gaps and reinforce corners.

I got a bit concerned when after one hour the resin still showed no signs of congealing. But I used a slow hardener: the next day, everything was as hard as glass. Nice! When I cut off the overhanging glass fiber I had to be carefull not to peel off the fiber from the wood. Cutting with a knife with a downward motion does the trick (and dulls the knife in no time :-).

Glueing in the thrusters

Thruster, inside Using copious amounts of epoxy glue I finally mounted the bow and stern thrusters. The operation went quite well, and I tried to fill all gaps and cracks I could find. This later will be crucial: apart from the drive shaft, the thrusters are the only interfaces between the the water and the ship's inside.

Thruster, outside

Cutting the thruster holes

Thruster holes, stern After trying for a long time to calculate the size of the thruster holes by mathematical means I resorted to cutting out circular holes, and spending a few hours grinding them into the desired shape and size by trying again and again.

Bow thruster, test fitting Really, with the bow and stern slanting in two angles I found it next to impossible to get a grip on the formulas. Event then, how do you paint a decent ellipse on a slanted piece of wood? Anyway, the crude approach worked, and the gaps I inadvertedly created hopefully can be bridged by epoxy glue.

Building the hull, part III: Bow

Bow, before glueing Putting together the bow was pretty much a repetition of assembling the stern. Since the bow has no flat parts it was even more difficult to fix the sides during drying.

Bow, being glued After holding the parts into place by hand for an quarter hour, I let some clamps and the weight of the computer battery do the rest. Tadaa - the body is complete (save the "lid").

Building the hull, part II: Stern

Stern, before glueing After some course and fast sanding with the band sander and lots of precision filing by hand the stern parts fit like a glove, and were ready for final processing.

Stern, being glued I first thought it would be easiest to glue the two parts together at the same time, but it prooved to be too much slipping and sliding. Since there is no right angle it was difficult to hold the parts in place with tools, and I ended up fixing the stuff with my hands for 15mins. After that, the glue was hard enough to dry on its own.

My fears that glueing the parts together in two separate sessions would result in a less than optimal fit turned out to be unfounded.

Assembling the mast

Mast, view from above (compass module) The mast is carrying the LED assembly (white light to the back and sides, blue light for the effect) and the electronic compass. I started with cutting a aluminum tube into shape (slanted cuts at both ends so the mast can be mounted at angle while the platform on top stays horizontal).

Mast, view from below (LED assembly) The LED board and the compass got mounted on a small circular plywould disk with some wire. The disk I glued onto the top of the mast.

Next was the cabling: a nine wire cable (from a serial cable) was pulled through the tube, and soldered to the LED assembly and the compass module. The other end is connected to the Basic Stamp (4 wires for the compass) and power drivers connected to the stamp outputs (one wire for the 12V lighting power supply, and 2 wires for the white and blue LED ground connection).

Building the hull, part I: Bottom, sides, and parts of the stern

Glueing side strut onto bottom First step: glueing struts to the side of the bottom. These struts will act as guides for attaching the side parts, and reinforce the edge and the bottom (the ship will weight about 12kg after all!).

Engine mounting The main engine has to be elevated from the bottom so the shaft can pass over the rear thruster while the propeller fits under the bottom of the stern part (see next picture).

This is the upper part of the stern. The flat bottom will just sit on or slightly under the water line. It supports the rudder and the rudder servo.

After cutting out the bottom I realized the V-shaped cut is 4mm too far in - ouch!, but the only erroneous cut so far (touch wood). So I cut out a V-shaped 4mm wide piece of wood, and glued it in. This worked better then I hoped/feared, and with the glass fiber/resin coating this should be no problem regarding stability.

The servo for the rudder is a pretty powerful device; I've been advised that some extra oomph is needed for a ship/engine of the size I'm building/using.