Electric fishing boat

[GarethC]

Wonder how it got on for rest of 2024


https://www.itllneverwork.boats/

[Stinsy]

Interesting. A few short-range ferries aside, boating is an area that presents significant challenges to moving away from FF. The energy-density and cost of diesel simply cannot be beaten. Boats typically run a very harsh duty-cycle too. A diesel car might be driven on journeys less than an hour 90% of the time and even when you are on a long journey you’re typically using 5% throttle cruising on the motorway. Whereas a boat engine can run flat out hour-after-hour.

I do think that fitting 1.8kW of solar on a boat with a 10kW motor is a folly…

[MikeNovack]

......Whereas a boat engine can run flat out hour-after-hour........

However not about boats in general but a LOBSTER BOAT. The duty cycle of a lobster boat is very atypical for a working boat.

a) Go at normal speed/full power to the first license area (normally a displacement type hull requiring comparatively low power up to "hull speed", (lobster boats do not go up "on plane")
b) Stop at first of your trap floats. Power just at idle to hold station. Connect to winch (electric winch) to hoist trap). Remove lobsters if any putting the legal size ones in the well (lobster boats are "smacks") and tossing the little ones back. Rebait trap if necessary and release.
c) Go to next float at low speed (it's probably less that 100' away). Back to "b".
d) Repeat until all the traps in this part of the territory are done. Then on to the next territory if any. That MIGHT be a distance away, up to a mile or two.

Do NOT touch the floats of another lobsterman! They ar very strict about the assigned territiries, handed down within families. OK, I can't speak about yours, but that's the way over here. Feuds with guns not unknown, aka "lobster wars.

The point is that this is a very unusual duty cycle for a working boat, one for which electric might be a good fit. If that boat had a decent size battery to provide a couple hours for that 10 KW engine, an 8 KW solar array not too small. Only using 10 KW going to territories, between the, back to the lobster dealer's pound, and home. The rest of the time using maybe 1 KW going float to float and for the winch.

[Stinsy]

......Whereas a boat engine can run flat out hour-after-hour........

However not about boats in general but a LOBSTER BOAT. The duty cycle of a lobster boat is very atypical for a working boat.

a) Go at normal speed/full power to the first license area (normally a displacement type hull requiring comparatively low power up to "hull speed", (lobster boats do not go up "on plane")
b) Stop at first of your trap floats. Power just at idle to hold station. Connect to winch (electric winch) to hoist trap). Remove lobsters if any putting the legal size ones in the well (lobster boats are "smacks") and tossing the little ones back. Rebait trap if necessary and release.
c) Go to next float at low speed (it's probably less that 100' away). Back to "b".
d) Repeat until all the traps in this part of the territory are done. Then on to the next territory if any. That MIGHT be a distance away, up to a mile or two.

Do NOT touch the floats of another lobsterman! They ar very strict about the assigned territiries, handed down within families. OK, I can't speak about yours, but that's the way over here. Feuds with guns not unknown, aka "lobster wars.

The point is that this is a very unusual duty cycle for a working boat, one for which electric might be a good fit. If that boat had a decent size battery to provide a couple hours for that 10 KW engine, an 8 KW solar array not too small. Only using 10 KW going to territories, between the, back to the lobster dealer's pound, and home. The rest of the time using maybe 1 KW going float to float and for the winch.

The solar array is 1.8kW, not 8kW!

[MikeNovack]

The solar array is 1.8kW, not 8kW!

Not terribly relevant, because unclear WHY bothering with a solar array ON the boat in the first place. Surely the added "top hamper" not worth the difference by simply increasing the battery size. The issue is duty cycle, which for a lobster boat is unusually low. If a working day involves an hour out (at 10 KW) and an hour home (at 10 KW) , the rest of the time maybe 1-2 KW, then a 40 KWh battery would do.

I didn't raise this before, because climate related, but I can't imagine any of our "down east" (coastal Maine*) lobstermen would want the top hamper of that solar array. Imagine what that would be like in winter, with the array collecting the weight of ice that would form on it. Even without that solar array, the weight of ice forming topside can badly affect stability.

(*) Maine was originally part of the colony of Massachusetts. Yes to the north, but sailing from the coast of Massachusetts to the coast of Maine you are mainly sailing east. I'm no sure why "down" east rather than "up" east except perhaps from the reality that you would NOT go into the teeth of a "nor'easter". Thus most of the days weather OK to go would be sailing downwind or at least a broad reach. << those of you who sail will understand>>

[Stinsy]

The solar array is 1.8kW, not 8kW!

Not terribly relevant, because unclear WHY bothering with a solar array ON the boat in the first place. Surely the added "top hamper" not worth the difference by simply increasing the battery size. The issue is duty cycle, which for a lobster boat is unusually low. If a working day involves an hour out (at 10 KW) and an hour home (at 10 KW) , the rest of the time maybe 1-2 KW, then a 40 KWh battery would do.

I didn't raise this before, because climate related, but I can't imagine any of our "down east" (coastal Maine*) lobstermen would want the top hamper of that solar array. Imagine what that would be like in winter, with the array collecting the weight of ice that would form on it. Even without that solar array, the weight of ice forming topside can badly affect stability.

(*) Maine was originally part of the colony of Massachusetts. Yes to the north, but sailing from the coast of Massachusetts to the coast of Maine you are mainly sailing east. I'm no sure why "down" east rather than "up" east except perhaps from the reality that you would NOT go into the teeth of a "nor'easter". Thus most of the days weather OK to go would be sailing downwind or at least a broad reach. << those of you who sail will understand>>

Solar panels on the roof of an electrically-propelled boat are a pointless waste of time!

I make exactly the same point regarding solar panels on the roof of electric cars. I'm passionate and evangelical about solar, but this seems to be an IQ test of sorts. A huge proportion of the population cannot intuitively quantify the cost/weight/complexity penalty vs the minuscule amount of energy you can expect to be generated in normal conditions.

On a sailing boat, where the propulsion comes from the wind (and maybe a smidge of electric) is a different KoF. In that case the primary purpose of the solar is to power the house loads and therefore they can definitely be worthwhile.

[MikeNovack]

On a sailing boat, where the propulsion comes from the wind (and maybe a smidge of electric) is a different KoF. In that case the primary purpose of the solar is to power the house loads and therefore they can definitely be worthwhile.

Well, even in the case of a sailing boat/ship doubtful IF it also has a motor (and thus propeller). When the motor not in use (mainly for docking, going through a bridge or narrow channel, getting out of embayment, etc.) the prop shaft is usually declutchhed so the prop can freewheel. But could also be used to generate some power to keep batteries charged. Deck panels maybe worth it if sailboat expected to spend a lot of its time berthed or at anchor.

Many of the discussions on topics like this totally ignore "duty cycle". Take trucks. It makes a BIG difference how that truck is used. Long distance highway hauling is a VERY different duty cycle than local delivery. The latter is likely a good candidate for EV right now because the vehicle spends a lot of its time stopped while unloading at each delivery spot and only some of its time driving spot to spot.

[John_S]

Well, even in the case of a sailing boat/ship doubtful IF it also has a motor (and thus propeller). When the motor not in use (mainly for docking, going through a bridge or narrow channel, getting out of embayment, etc.) the prop shaft is usually declutchhed so the prop can freewheel. But could also be used to generate some power to keep batteries charged.

Speaking from experience, if a freewheeling prop shaft is connected to a generator, it will take at least a knot off the boat speed and few sailors would tolerate such a reduction in speed, especially if sailing long distances and/or trying to escape bad weather.

Sure, it is one way to charge the battery, but it is not without its draw backs.

[GarethC]

True, but yachts struggle to go much beyond their hull speed. When there's excess wind that's not adding much to speed, that might be the appropriate time to charge the battery from the propeller. Not that frequently I'll grant.

[MikeNovack]

Speaking from experience, if a freewheeling prop shaft is connected to a generator, it will take at least a knot off the boat speed and few sailors would tolerate such a reduction in speed, especially if sailing long distances and/or trying to escape bad weather.

Sure, it is one way to charge the battery, but it is not without its draw backs.

As noted, a displacement hull won't go faster than hull speed in any case. But more to the point, if generating electricity from a freewheeling prop, the amount should be adjustable. I''d say trying for way too much if it took a knot off the speed. You should NOT be trying to maximize the electricity produced, which I suspect the case when you say "took a knot off the speed". Note that the rotational speed will be varying only a little (from what is optimal at hull speed, given the prop pitch) so the generator itself will need to be adjustable.