ESPcat Neglected Bottom

In this troubled world, there are few sadder sights to see than a neglected bottom. This is how the horrific scene unfolded. I was just about to the annual maintenance haul-out of Borderline in November 2021, when events were overtaken by a family illness that put everything on hold. After 6 months of medical heroics, things are miraculously back on track I can turn my attention back to bottoms. Unfortunately every species of sea creature has taken up residence on Borderline’s bottom and it is a tragic sight to behold.

The state of Borderline’s bottom was so horrific that I decided not to photograph it. I feared you blog buddies might not be able to handle it. Things were looking bad so I loaded up the Boat Guy’s trailer with the cradle frame and set off for the boating club. Roger, the Boat Guy is very generous with his trailer.

All these bits have to be added to the haul-out cradle in order for Borderline to fit onto it.

Just a bit of magic and the cradle is ready for Borderline,

Now just lower the cradle down into the water on its railway track and wait for the tide to come in.

As you can see I have already removed all the muscles, oysters and barnacles with my water blaster because it was all just too horrible to show to you blog buddies.

The plan is to re-do the antifouling paint and replace to two ageing 8 hp motors. One motor is a 2 stroke long shaft and the other is an 8hp, 4 stroke, high thrust long shaft. Yes, I know, they are not exactly a matching pair. I am replacing them with a pair of 9.9 Yamaha, 4 stroke, long shaft, high thrust motors which are much newer and hopefully have a bit more grunt.

Now you blog buddies might be wondering, what is a pair of gasoline outboard motors doing on a solar powered boat. Well the answer is that I always planned to do at least one season on fossil fuel motors before installing electric motors driven by solar. I want to first discover what performance I can get with well proven gasoline motors and then try to duplicate that performance with solar electric motors.

In an earlier life, Borderline was a racing, sailing catamaran with the following specifications:

model Eaton 8.5m Catamaran
loa 8.5m
lwl 8.2m
beam 6.3m
displacement 1,000kg (I was told the was actually 1,200 kg)
draft 1.8m boards down, 0.250m boards up
maximum air draft 1.26m
engine Honda 15hp four-stroke outboard
propeller Yamaha high thrust
fuel 20 litres
holding tank 40 litres
cruising speed under motor 8 knots
max speed 28 knots

Borderline is a bit heavier now at around 1,500 kg thanks to a large cabin and water tank but she should still make 8 knots with 2 x 9.9 hp = 18.8 hp engines with high thrust gearing. Once Borderline is fitted with solar panels, batteries and electric motors she will have a displacement of close to 2,000 kg. The twin S20 outboards by Golden Motors (yes golden!) are 10.5 kw input. These motors claim to be equivalent to 20 hp but of course that is complete bullshit. The 10.5 kw is the input power so at an estimated 85% efficiency, I expect the output to be 8.9 kw. 8.9 kw divided by 746 watts per horsepower gives 11.9 hp not 20 hp!

In any case, I am hopeful that Borderline will make her target speed of 8 knots with her solar electric propulsion system. I hope to begin installing the solar electric bits in about this time next year. Meanwhile, I have a lot of work to do paying close attention to a badly neglected bottom. Replacing the outboards should be quite a drama.

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