So … after filling the day tank with fuel (15 gallons), it apparently drained (siphoned) out. I installed a Lowrance/Navico Fluid Level Sensor to put the fuel level of the day tank (15 gallons) on the NEMA 2000 network via the sending unit. Once I was able to monitor the fuel level, I discovered the fuel was indeed being siphoned. After I examined the plumbing, I decided to switch the engine return (without siphon tube) and overflow hoses (with a siphon hose) to/from the day tank, and this fixed the problem.
After more than four months on the hard – during which time she received a new fuel system, a bow thruster, bottom paint, etc. – she was put back in the water this morning. The launch was not without its problems. The dripless seal is dipping (and needs to be adjusted) and the engine would not run. Eventually, the problem was traced to an oil pressure sending unit that is attached to the alarm system. Because the sending unit was not tripping, the electric fuel pump was being shut off. I “hot-wired” the sending unit so the boat could be moved from the ramp to the slip.
A 15 gallon aluminum day tank was installed in the engine room on the shelf where the genes used to be mounted. Since it is located above the engine, the diesel is gravity-fed, which reduces the chances of an air blockage in the line.
Since the day tank will be filled from the main tank via the fuel polisher, the fill line for the day tank was located in the bottom of a lazarette. The fill line will only be used for emergencies, were for some reason it is not possible to transfer diesel from the main tank.
The anchor roller passes through the bow sprit. While steel tubes were used to prevent the bolts for the roller bracket from digging into the wood of the bow sprit, the bracket has still shifted causing the roller to dig into the bow sprit platform. I designed a brace and used SendCutSend to manufacture it out of 316 steel.
The bracket is bolted to the bow sprit with lag bolts behind the axial of the roller (outlined in red).
The bow thruster has been installed. To make the job easier, the equipment was installed from the bottom up, beginning with a bilge pump and the electronics. The electronics comprise of a Victron SmartShunt 1000 Amp Battery Monitor, a Victron DC-DC Orion-Tr Charger (which connects the lithium batteries that are under the V-berth to the house battery bank in the engine room), a Blue Sea Systems 7713 ML-RBS Remote Battery Switch (that can be used to remotely disconnect the bow thruster from the battery bank), and breakers/fuses. The electronics were mounted on a board to make it easier to service in the future. Note also two selves were fiberglassed in, a small shelf for the bilge pump and a larger shelf (at the bottom of the photo) that will be used to support the thruster motor. On the left of the photo is a support that will be used to support a third shelf for the batteries.
The transmission for the bow thruster was installed in the tube and a priming paint was applied.
A support for the bow thruster’s motor was fabricated from fiberglassed marine plywood. The stainless brackets were designed in Fusion 360 CAD software and were fabricated by SendCutSend.
A custom battery pan was also manufactured by SendCutSend.
The fiberglass tube for the bow thruster was installed. Under the V-berth, tie lines were dropped and pilot holes were drilled on the port and starboard side of the hull.
Using a string and two points on the keel, I confirmed the pilot holes were centered, then a jig was passed through the two pilot holes. The jig comprised of a steel rod that was sharpened to a point on one end and bent twice such that the point was a distance from the axis of the rod that was the radius of the fiberglass tube. Note the two red chalk marks that were used to confirm the pilot holes were centered (made by tying a piece of chalk to the end of a string that was taped to the leading edge of the hull). The jig was then used to scribe the hull.
A saber saw with a diamond blade was used to cut out the oval that was scribed.
Note the hull is 1-1/4″ thick where the holes were cut.
The tube fit the holes that were cut perfectly.
Before glassing the tube in, the hull was ground down past the gel coat.
Once glassed in, the excess tube was cut off, leaving enough of the tube protruding to create the leading hydrodynamic edge.
After glassing in the outside of the tube, the leading edge was flared to improve hydrodynamics. Cabosil (collodial silica), a very hard material, was used to flare the leading edge.
Low density (fairing) filler was used to smooth the installation.
My sister ship Arabesque (also an Alajuela 38) and the Aegir-Ran happened to both be on the hard at Marina Seca in San Carlos, just a few boats away from each other. I had only arrived in San Carlos that day and had taken the owner out for a couple of beers and some almejas chocolatas (chocolate clams) at one of our favorite restaurants, La Manga Restaurante Doña Rosita. The Arabesque was to be moved from the work yard to storage at 2:00 PM, and we arrived at the yard exactly at 2 only to find that the boat yard had begun to move Aegir-Ran, not Arabesque. While there are many differences between the boats (e.g., Aegir-Ran had a hard dodger), the hulls of the boats are almost identical, right down the the color of the paint of the hulls (Awlgrip Insignia White) and the waterline stripes. Flagging the workers down, we all had a good laugh about the incident, and in the days following, I still poke fun at them for trying to “steal” the Aegir-Ran.
Here is a photo of the Aegir-Ran on that day:
Here is a photo of the Arabesque being hauled to storage:
ρ (rho) represents the specific mass of air = 0.0752 lb/ft²
V is the velocity of the air in ft/s, where 1 knot = 1.688 ft/s
The wind-draft of the boat can be determined by multiplying the wind pressure by the wind draft area. The wind draft area is determined by the shape and the dimensions of the of the boat (its windage) and the wind angle, and the greatest wind-draft is created if the wind is at 90 degrees to the boat. An efficiency reduction factor is generally applied to account for windage, and a value of 0.75 is frequently used. To calculate the required torque to rotate a boat, we need to know the wind pressure and the length of the boat.
The Aegir-Ran has a LOD = 36 ft and the freeboard is about 3 ft, giving wind draft of 36 x 3 = 108 sq ft. Adding the cabin, hard dodger, and the sail pack adds perhaps 50 sq ft, which is why the efficiency reduction factor is often used. I will assume the lateral draft is 200 sq ft and I will not use an efficiency factor. Assuming we want to counteract a wind force of 25 knots, the wind pressure is:
P = 1/2 × (0.0752 lb/ft²) × [25 knots x 1.688 ft/(s x knot)] = 1.59 lbf/sq.ft
To counteract this wind pressure, we sill need the following amount of torque:
T = 1.59 lbf/sq.ft x 200 sq/ft x 36 ft/2 = 5,724 ft.lbs.
The thrust-force required is the torque divided divided by the distance from the bow thruster to the pivot point. In our case, we will assume we want to pivot about the stern, do the distance is essentially the LWL = 33 ft:
F = 5,724 ft.lbs. / 33 ft. = 173 lbf.
I have decided to install a 12 V Ventus bow thruster. Examining the specifications of the models, it seems the BOW7512D is the best model with a maximum thrust of 180 lbf.
While anchored in Bahia San Padro and waiting for a weather window to head south, I noticed a rock arch in the hills above the bay (circled in red).
Asking the locals, I am told it is called “Big Trunk Elephant” (“Elefante de Trompa Grande”). It took about two hours to hike to the arch, first through washes to the base and then bushwhacking to the arch itself. Once there, I discovered the rock to be loose and dangerous to climb. Also, it appeared that rock climbing would be needed to actually get to the hole. Perhaps the backside would be more accessible.
