Oceanvolt Servoprop regen tested by UMA

[Joli]

What's old is new again....

http://www.nooutage.com/images/q01-water.jpg

[BigBeakie]

Ahhhh, from the sublime to the ridiculous......

Was once on a trip in the Coral Sea on a boat that was using a tow generator as illustrated, and what a PITA it was. Also quite ineffective re power harvested. The skipper lost it a few trips later to a shark. So it turned out to be an expensive fishing lure[emoji23]

Needless to say, he didn't replace it.

[Jim Cate]

Originally Posted by BigBeakie

Ahhhh, from the sublime to the ridiculous......

Was once on a trip in the Coral Sea on a boat that was using a tow generator as illustrated, and what a PITA it was. Also quite ineffective re power harvested. The skipper lost it a few trips later to a shark. So it turned out to be an expensive fishing lure[emoji23]

Needless to say, he didn't replace it.

Well, BB, which is which? My personal experience with a home brew trolling generator was that it was something of a PITA to use, but that it meant ending a passage with near full batteries vs having to run the engine every few days en route. And all for an out of pocket cost of less than 100 USD (back a few years, though). Power production was on the order of two kwh per full days running... but we didn't consume that much most days (by far) so it was only run part time.

That, to me, was pretty sublime! And BTW, we towed that thing for some years and several ocean crossings, plus many shorter passages and never lost a spinner to a shark or any other cause. I personally don't believe the shark theory often expounded when one does depart, at least for systems like mine where the spinner was a `14 mm s/s shaft around a meter in length with a 6 hp outboard prop spinning away on its aft end... not all that easy to bite off!

This was in the days before cheap and effective solar was around. Now we depend upon the sun... but I'd consider building another troller if we were planning any more long passages, for they are a great adjunct to solar.

Jim

[Adelie]

Originally Posted by Jim Cate

Well, BB, which is which? My personal experience with a home brew trolling generator was that it was something of a PITA to use, but that it meant ending a passage with near full batteries vs having to run the engine every few days en route. And all for an out of pocket cost of less than 100 USD (back a few years, though). Power production was on the order of two kwh per full days running... but we didn't consume that much most days (by far) so it was only run part time.

That, to me, was pretty sublime! And BTW, we towed that thing for some years and several ocean crossings, plus many shorter passages and never lost a spinner to a shark or any other cause. I personally don't believe the shark theory often expounded when one does depart, at least for systems like mine where the spinner was a `14 mm s/s shaft around a meter in length with a 6 hp outboard prop spinning away on its aft end... not all that easy to bite off!

This was in the days before cheap and effective solar was around. Now we depend upon the sun... but I'd consider building another troller if we were planning any more long passages, for they are a great adjunct to solar.

Jim

What did you use for the generator/alternator?

[donradcliffe]

I didn't lose a spinner, I lost the whole bloody hydro generator system overboard at 3 am between Port Stephens and Coffs Harbor While I was reaching at 8 knots, something really big hit the spinner, broke the generator out of its mounting, and broke a 5/16" safety line. I replaced it because it was the best alternative source of power on the boat.

[Jim Cate]

Originally Posted by Adelie

What did you use for the generator/alternator?

A surplus 32 vdc perm mag tape drive motor... commonly available during the early and mid 80s.......

Jim

[Jim Cate]

Originally Posted by donradcliffe

I didn't lose a spinner, I lost the whole bloody hydro generator system overboard at 3 am between Port Stephens and Coffs Harbor While I was reaching at 8 knots, something really big hit the spinner, broke the generator out of its mounting, and broke a 5/16" safety line. I replaced it because it was the best alternative source of power on the boat.

Ooohhhh.... I HATE it when that happens!


Jim

[Adelie]

Originally Posted by Jim Cate

A surplus 32 vdc perm mag tape drive motor... commonly available during the early and mid 80s.......



Jim

I’m considering what it would take to adapt a ceiling fan motor. Good low rpm production. Wondering if an MPPT controller would work to match production to the batteries?

[BigBeakie]

The line broke on Brian's generator and he saw the thrashing on the surface as the shark grabbed it and the line parted. It sounds like something similar happened to Don. Glad to hear your unit stayed with the boat, but your experience, is just your experience. So what is the basis of your personal incredulity that a shark or marlin would,or could, not break one of these off? The power of these apex marine predators is extraordinary, I assure you. What would be your alternate idea as to why these are lost? Rope chafe? Hockling stress on the line?

My inference was the Servoprop technology is sublime putting out about a kilowatt an HOUR at 8 knots compared to a towed generator putting out a comparatively ridiculous 50 to 80 watts per hour.

[Jim Cate]

Originally Posted by BigBeakie

The line broke on Brian's generator and he saw the thrashing on the surface as the shark grabbed it and the line parted. It sounds like something similar happened to Don. Glad to hear your unit stayed with the boat, but your experience, is just your experience. So what is the basis of your personal incredulity that a shark or marlin would,or could, not break one of these off? The power of these apex marine predators is extraordinary, I assure you. What would be your alternate idea as to why these are lost? Rope chafe? Hockling stress on the line?

My inference was the Servoprop technology is sublime putting out about a kilowatt an HOUR at 8 knots compared to a towed generator putting out a comparatively ridiculous 50 to 80 watts per hour.

Well, I just fail to believe that a very large shark would attack the thing. I surely must have been in the vicinity of such beasts in all the miles we towed and no such attack eventuated. And in Don's case, no data presented to determine what caused the loss. Could be a big fish, who knows? It is a potential failure mode, t hat I'll admit. Frequency of occurrence is debatable.

But as to sublimity... well, first we are not really comparing apples here. My boat was not capable of sustained 8 knot speeds, so the metric is flawed. On the occasions that we reached 7 knots our home brewed troller would output well over 20 amps... and then leap out of the water. It was designed to work at our cruising speeds, not some unattainable velocity... and I suspect that the output of the OV setup at 6 knots wouldn't be so sublime.

But the real subject of my post was to point out that if one uses a different metric, say amp-hours/day per dollar invested, the comparison would look differently. For a fiscally limited cruiser, the OV package is pretty dear just to keep the batteries full. And not all cruisers expend multiple kwh per day.

The average cruiser can't engineer a home brew OV system, or anything like it. Nor can many afford one. But a simple troller is demonstrably possible. I don't think this is ridiculous at all.

Jim

[BigBeakie]

I fail to understand your disbelief that a large shark would attack something zooming along at the surface making lots of bubbles. They bite whatever they decide to bite, that's what apex predators do.

Ok fair enough regarding the output vs speed consideration. But at 6 knots the Servoprop would still output an order of magnitude more than the towed contraption, and at 48 volts, not 12v. So multiply the 10 times more watt/hrs at same boat speed by another 4 times, for the voltage difference.

And at how many knots would your generator push your boat in the calms?

This is a bit like bemoaning the passing of the cart & horse versus a Tesla [emoji6]

[Jim Cate]

For the cruisers who could afford a Tesla, yep, it's true... horses need not apply for the position. For the budget limited, a smaller, simpler and far less expensive means of augmenting the charging of batteries is a worthwhile idea.

And no one was suggesting a troller as a means of supplying motive power except you, BB. What a silly argument...

So, that's it for me for now.

Jim

[BigBeakie]

Originally Posted by Jim Cate

For the cruisers who could afford a Tesla, yep, it's true... horses need not apply for the position. For the budget limited, a smaller, simpler and far less expensive means of augmenting the charging of batteries is a worthwhile idea.

And no one was suggesting a troller as a means of supplying motive power except you, BB. What a silly argument...

So, that's it for me for now.

Jim

From the Sailing Today article on Hydrogenerators - on test:

" Early models towed an impeller on a long line behind the boat, which was attached to an alternator on board. But their trailing impellers were often bitten off by large fish and they frequently tangled up when fouled or if not retrieved correctly."

Apparently others are also under the impression that these can be lost to big fish.

You commented on the cost effectiveness of the Servoprop as a hydrogenerator, as if it's value was just as a hydrogenerator. I was just pointing out that primarily it is a propulsion motor that also happens to be the most efficient hydrogenerator on the market. So that has to be considered in the cost benefit consideration, plus maintenance benefits vs diesel etc.

Sure, as in many things, the cost-benefit may suit some, and not others. So be it.

[Joli]

For those concerned about shark attacks....
https://www.emarineinc.com/brands/WattandSea.html

[malbert73]

From Uma’s latest video, they were sailing 7 + knots and generating above 500W. Without commenting on cost/benefit of OV, it seems pretty respectable as an adjunct to solar to maintain house loads.