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Budget Bow Thrusters - $1500
Installation
Installing the bow thrusters on the boat was pretty easy. This being a sail boat there where considerations on placement of the budget bow thrusters, see the next page for details.
- Pontoon mounts, Cut some starboard ½” and ¼” strips. One ¼” overlapping the gunwale. Longer bolts where needed. Still need to drill out and epoxy the cored deck. I chose to use pontoon mount because of the boats layout. You may well be able to use the standard mounts.
- The controller will need to be as close to the battery and motor as possible to reduce the amount of wire needed as the size of wire needed to handle the amperage draw is large and pricey. Dismantle the head and cut the pot (speed control) wires. Unplug the motor wires.
- The stock shafts where to short for my boat so I ordered longer ones. Cut the original shafts off and chiseled out the remaining carbon fiber shaft. Painstaking work because you need to take care not to damage the threads or wires. Was advised by the manufacturer to heat up the casing to loosen the locktight and they would screw out but the carbon shaft simply caught alight. So much chisel work was needed. These composite shafts are really tough!
- Extended the wires using 8AWG wire cause you have a longer shaft and need to reach the plug socket. Drilled two 1 1/8” holes to install the plugs.
- Mount each controller in line with the batteries and where the motor plug is to be placed. This is to keep the wire run as short as possible and consequently lessen the voltage drop or size of wire needed.
- Install big 150A main fuse and two 60A fuses next to each controller.
- Ran some small controller wires from the controllers to helm and soldered them where the pot wires where cut on both the controller and pot.
- Mounted the speed controls in original casings and use old shafts as mounting poles. This gives me two variable speed controls at the helm.
Testing
Speed : 1.5 knots with both motors full forward (might have picked up a bit more speed but I was short on space. This speed was reached in two boat lengths.
Turning : 90 degree turn done in 14 seconds. Without using rudders or the main engine.
The initial test was disappointing, the amperage draw is only 84 and is, according to the manufacturer meant to run at 100, 50 amps each, which is 0.67HP each, as opposed to the published 0.8hp. According to prop calculations 100amps should push her at 2.9 knots and 84 amps at 2.7 knots, so 1.5 is disappointing.
Which leads me to believe these, stock, wheedles props aren’t as efficient as they could be. According to the manufacturer they are designed for around 4 knots. I have ordered some larger 3 blade props which claim additional power. I’ll post an update when they arrive.
Turning ability however is reasonably good in calm. I tested this without the use of the rudder or outboard and was able to navigate the tight marina single handed with ease. She did turn on her axis. I noticed afterward I forgot to pull the main prop out the water but I doubt this slowed it down much.
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