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Old 08-02-2018, 01:27   #1186
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Re: Oceanvolt Hybrid Motor

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I was thinking of the Erie Canal where every small town has converted the old commercial dock into free dockage for pleasure boaters and most have shore power. They really don't pull up to the shore to tie off along most of the route.

But see my previous response. Assuming it's a leisurely trip (which is common for those wandering canals), solar is viable for most or all of the travel. I was probably overstating the demand with 10kw. 5-8kw will probably get you 4mph. Biggest issue would be shade.
Traversing the Eire canal is hardly "canal boating". And I dunno how you come up with your power requirements. The canal boat we traveled on was about 40 feet OAL, steel bargelike construction and ran a 4-108 at around 2/3 throttle to do its leisurely 4 knots. This was a very typical older canal boat, and I'm sure that there are more easily driven hulls around... but 5-8 kw seems completely inadequate to drive the average canal cruiser at 5 knots.

Pipe dreams don't cut it in reality.

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Old 08-02-2018, 02:05   #1187
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Re: Oceanvolt Hybrid Motor

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Traversing the Eire canal is hardly "canal boating". And I dunno how you come up with your power requirements. The canal boat we traveled on was about 40 feet OAL, steel bargelike construction and ran a 4-108 at around 2/3 throttle to do its leisurely 4 knots. This was a very typical older canal boat, and I'm sure that there are more easily driven hulls around... but 5-8 kw seems completely inadequate to drive the average canal cruiser at 5 knots.

Pipe dreams don't cut it in reality.

Jim
It's a boat.
It's on a canal system.
How is it not canal boating?

Also, you bumped it up to 5kts (5.8mph) and cut the available power. I used 4-5mph and a 10kw motor as a suggested starting point.

Then again, what were you dragging if it took 2/3 throttle with a 50hp engine. Was there 20yrs of growth on the bottom?

If the old style canal boats really are that bad, a more efficient hull design is definitely in order. Only place you are really stuck with an old style is on the UK narrow canals with a 7' max beam. Most anyplace else 12-15' beams can reasonably traverse the canals.

On the Eire our 34' cat with a 25hp engine was rarely above 1/4 throttle and we were running around 5-6mph. 4mph in calm conditions is barely above idle. 10kw in those conditions is plenty if not overkill. A dedicated canal boat built on similar hulls would be even more efficient.

It's when you get onto open water where wind and waves can really kick your butt and you might have to run for a long time at peak output. That's where it becomes questionable if 10kw is enough.
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Old 08-02-2018, 09:03   #1188
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Re: Oceanvolt Hybrid Motor

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IThen again, what were you dragging if it took 2/3 throttle with a 50hp engine. Was there 20yrs of growth on the bottom?
Jim did say:
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The canal boat we traveled on was about 40 feet OAL, steel bargelike construction
So weight and hull form are obviously critical.

I saw something interesting yesterday: "What powered the Falcon Heavy rocket that sent the Tesla electric roadster into orbit? 160,000 gallons of kerosene."

Horses for courses.
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Old 08-02-2018, 11:15   #1189
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Re: Oceanvolt Hybrid Motor

Yes, but he ran out of fuel on the center stage and lost that rocket.

But the landing of the outer boosters was way impressive.
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Old 08-02-2018, 12:08   #1190
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Re: Oceanvolt Hybrid Motor

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It's a boat.
It's on a canal system.
How is it not canal boating?
It's out of my personal experience range, but I was under the impression that folks that traversed the Eire were simply getting from the Great Lakes to the Hudson, en route to some other destination. The canal boats that we encountered in France were full time residents of the canals and rivers of Europe and spent their entire lives on those waters.
That's w hat I associate with the "canal boating' lifestyle.

The majority of those boats were elderly, 35 to 60 odd feet in length, relatively narrow for their lengths and pretty rectangular in shape. Definitely not easily driven, and the one we were on was over fifty years of age and was a pig to drive forward and uncontrollable in reverse. On the other hand, she was comfortable, had a good galley (important in France!), was very rugged for dealing with crowded and rough locks... and had cost the owners around 30 grand US. There were more modern boats, mostly in the charter fleets, and they looked mostly like any other plastic motor boats. They were scorned by the live aboard canal cruisers, but were likely more easily driven shapes and weights. I was never aboard one and have no opinion about their suitability.

She had a steering station atop the house which ran most of her length), and that's where we drove from most of the time... except when passing under low bridges. Then we would have to strike the shade umbrellas and steer from below, for air draft is a big issue with these sorts of canal boats... and that just might be a limiting issue with big solar arrays. Fixed arrays would need to be high enough to stand under or tough enough to be walked on to be practical, and this might well limit their usefulness. It's too bad, for there is often a lot of horizontal area on such top decks... perhaps some sort of collapsing array could be designed and serious wattage deployed.

Sorry about the rambling reply! It was an attempt to explain why I doubted that full solar electric would be real practical for a "real" canal boat in typical canal cruising in Europe. No doubt one could design a full solar boat for such usage, but it would be very different from those now in use.

Jim
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Old 08-02-2018, 21:01   #1191
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Re: Oceanvolt Hybrid Motor

Yes Val, we ordinarily have no problem with the 4 or 6 amp shore power. I was just experimenting with the variable speed electric hot water heater we have. If I set it higher than 2 out of the 6 heating speeds it trips the breaker on shore. Also our house battery charger is variable and if set too high it also trips the breaker on shore.

The cost of the shore power electricity is that high because the town probably uses it as a revenue generator. I'm sure electricity supplied to homes and businesses is much cheaper.
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Old 10-02-2018, 05:36   #1192
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Re: Oceanvolt Hybrid Motor

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Jim did say:

So weight and hull form are obviously critical.
Weight is critical to acceleration but the impact on cruising speed should be modest. A little more as you sit a touch deeper but a 50hp at 2/3 throttle is several times what similar size vessels need for modest speeds.
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Old 10-02-2018, 05:56   #1193
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Re: Oceanvolt Hybrid Motor

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It's out of my personal experience range, but I was under the impression that folks that traversed the Eire were simply getting from the Great Lakes to the Hudson, en route to some other destination. The canal boats that we encountered in France were full time residents of the canals and rivers of Europe and spent their entire lives on those waters.
That's w hat I associate with the "canal boating' lifestyle.

There are certainly people who do just use it as a way to get from A to B but there are people who do the same thing in Europe to get from the north to the med. We came across a fair number of people wandering back and forth, up the Champlain Canal or across to the Trent-Severn (getting across the lake would need a little planning for a slow canal boat but doable if you don't do it often.) We spent 3 months and loved it.

The majority of those boats were elderly, 35 to 60 odd feet in length, relatively narrow for their lengths and pretty rectangular in shape. Definitely not easily driven, and the one we were on was over fifty years of age and was a pig to drive forward and uncontrollable in reverse. On the other hand, she was comfortable, had a good galley (important in France!), was very rugged for dealing with crowded and rough locks... and had cost the owners around 30 grand US. There were more modern boats, mostly in the charter fleets, and they looked mostly like any other plastic motor boats. They were scorned by the live aboard canal cruisers, but were likely more easily driven shapes and weights. I was never aboard one and have no opinion about their suitability.
Most of the dedicated canal cruisers we saw were houseboats but just about any reasonable boat that could get under 15' would work.
It doesn't have to be an old steel barge.


She had a steering station atop the house which ran most of her length), and that's where we drove from most of the time... except when passing under low bridges. Then we would have to strike the shade umbrellas and steer from below, for air draft is a big issue with these sorts of canal boats... and that just might be a limiting issue with big solar arrays. Fixed arrays would need to be high enough to stand under or tough enough to be walked on to be practical, and this might well limit their usefulness. It's too bad, for there is often a lot of horizontal area on such top decks... perhaps some sort of collapsing array could be designed and serious wattage deployed.
We did a Viking River Cruise last year and while it wasn' solar,
they had shade on much of the uppe deck and it was really simple to fold down. Something similar could easily be adapted to a small canal cruising boat.


Sorry about the rambling reply! It was an attempt to explain why I doubted that full solar electric would be real practical for a "real" canal boat in typical canal cruising in Europe. No doubt one could design a full solar boat for such usage, but it would be very different from those now in use.

Jim
No problem rambling. I think once you switch to electric propulsion, you are no longer a traditional boat. We don't have to stick to traditional heavily built boats unless you really feel the need to look traditional.

Our Gemini is considered lightly built but we've done over 60 locks of variety of styles and never had a concern about it getting beat up in the locks. Assuming 15w/sft and ditch the mast, we could fit around 3600w of solar without impacting any air clearance or deck space that currently get's walked on (basically over the salon raised cabin back over the davits).
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Old 10-02-2018, 08:36   #1194
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Re: Oceanvolt Hybrid Motor

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Weight is critical to acceleration but the impact on cruising speed should be modest. A little more as you sit a touch deeper but a 50hp at 2/3 throttle is several times what similar size vessels need for modest speeds.
Weight = displacement, regardless of the hull form. Power required for a given speed is directly proportional to displacement -- take any hull and add weight, the power requirement increases. In fact, to a first-order approximation doubling the weight will double the power required to maintain a given speed (I'm talking about pure displacement hulls, moving under hull-speed).

Yes, the hydrodynamics of the hull also matter -- a shoebox hull will require more power than will a long, skinny hull of the same displacement -- but weight also matters a lot.

And yes, 50 hp of propulsion may be more than is needed for some boats, in some situations.
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Old 10-02-2018, 09:08   #1195
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Re: Oceanvolt Hybrid Motor

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Weight = displacement, regardless of the hull form. Power required for a given speed is directly proportional to displacement -- take any hull and add weight, the power requirement increases. In fact, to a first-order approximation doubling the weight will double the power required to maintain a given speed (I'm talking about pure displacement hulls, moving under hull-speed).

Yes, the hydrodynamics of the hull also matter -- a shoebox hull will require more power than will a long, skinny hull of the same displacement -- but weight also matters a lot.

And yes, 50 hp of propulsion may be more than is needed for some boats, in some situations.
A heavier vessel will need a bit more power but it's not a linear relationship to the weight of the boat. Once you get it moving, momentum does most of the work. So if he said 10-20% more power maybe even 30%, I might buy it but this works out to around 600% more power than I would expect from a similar size but lighter vessel.

Also, at low percentages of hull speed hull form is far less important. It's as you approach hull speed that it makes a big difference. (60' boat should have a hull speed north of 10kts so 5kts would only be 50% of hull speed)

Where weight makes a big difference is accelerating.

But regardless, there isn't really a driving need to use a heavy, highly fouled, horrible hull form, so you can reduce the required power drastically.
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Old 10-02-2018, 10:41   #1196
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Re: Oceanvolt Hybrid Motor

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A heavier vessel will need a bit more power but it's not a linear relationship to the weight of the boat. Once you get it moving, momentum does most of the work.
Below hull speed, water resistance is proportional to displacement. Displacement = weight.

Technically speaking, momentum does *zero* work. It does of course reduce the need to speed up again after hitting a wave, but it doesn't affect the total power requirements.

And you are probably right about the power used on the heavy barge, but I suspect that there is an apples / oranges thing going on there.
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Old 10-02-2018, 21:26   #1197
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Re: Oceanvolt Hybrid Motor

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Below hull speed, water resistance is proportional to displacement. Displacement = weight.

Technically speaking, momentum does *zero* work. It does of course reduce the need to speed up again after hitting a wave, but it doesn't affect the total power requirements.

And you are probably right about the power used on the heavy barge, but I suspect that there is an apples / oranges thing going on there.
Anyway back to the point: It's very much viable to build a EV or hybrid canal cruiser that meets cruisers current needs with little or no negative impact.
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Old 10-02-2018, 21:39   #1198
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Re: Oceanvolt Hybrid Motor

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Anyway back to the point: It's very much viable to build a EV or hybrid canal cruiser that meets SOME cruisers current needs with little or no negative impact.
Would you accept that edit? You have not explained how non-marina or dock oriented canal boaters would recharge routinely.

Jim
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Old 10-02-2018, 21:59   #1199
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Re: Oceanvolt Hybrid Motor

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Below hull speed, water resistance is proportional to displacement. Displacement = weight.
No, significantly below hull speed, when wavemaking drag is much smaller than viscous drag, water resistance of a given hull at a given speed is approximately proportional to wetted area.

How wetted area depends on weight with a given hull depends on shape, but it's never a linear relationship. The shallower the hull is compared to it's beam at waterline, the less any extra weight increases wetted area percentage wise.
If one wants to compare with absolute values instead, like how many more sqm for each extra kg of mass, then it's the water plane area and its perimeter length which counts. The more water plane area, the less is the increase of immersion per additional unit weight. And extra wetted area is extra immersion times perimeter length. For a very narrow canal boat, the perimeter length is almost a constant, and thus rate of increase of wetted area for a given extra displacement becomes close to inversely proportional to beam at waterline.
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Old 10-02-2018, 22:09   #1200
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Re: Oceanvolt Hybrid Motor

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Would you accept that edit? You have not explained how non-marina or dock oriented canal boaters would recharge routinely.

Jim
The infrastructure for shore power recharging is either available at regular intervals/distances, or at least it could easily be made so. If some cruiser chooses not to use it, it his/her own problem if batteries of their boat run out of energy.
There is not much difference with needs of electric cars for recharging. The publicly available infrastructure for that is already expanding at least in Europe, and would assume elsewhere as well.
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