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Old 12-12-2015, 09:28 PM   #101
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Just curious - what wears out in a mold? I could see how the finished surface might need some touch up since the gel coast surface of the boat is no better than the mold surface. But what else?
Eventually the mold will experience either some warp or some cracking of some sort just from the repeated stress. However, it's highly unlikely in moderate production boats. I've known molds to still be perfect after being used for over 200 65' boats. However, if you're up to thousands of boats out of a mold like some of the volume small boat builders then the accumulated force on them affects them.
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Old 12-12-2015, 09:56 PM   #102
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Eventually the mold will experience either some warp or some cracking of some sort just from the repeated stress. However, it's highly unlikely in moderate production boats. I've known molds to still be perfect after being used for over 200 65' boats. However, if you're up to thousands of boats out of a mold like some of the volume small boat builders then the accumulated force on them affects them.
In addition to the above the alignment of the three pieces that make up the hull is something that requires attention. Some molds will use threaded inserts to bring together the piece's. Inserts wear over time but it is mostly the finish of the molds that are most concerning.
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Old 12-13-2015, 12:42 PM   #103
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...We took a hard look the SeaKeeper Gyro system but struggling to get my head around the concept, time for system to come on line (45 minutes) need to run the generator (possible to run off the inverter but would have limited run time using batteries thus you really need the generator running full time) and the space required in the engine room.

John
John, many thanks for sharing all of this.

Your mention of the gyroscopic stabilizer piqued my interest. My first thought was that the power draw once spun up would be pretty low. I have an amateur interest in energy storage, and large flywheels on really good bearings don't typically need much energy to maintain speed. But I suspect that friction loss would increase in proportion to the stabilization required.

In any case, looking at the manufacturers data sheet it appears that the maximum power required is about 2.2 kw. I would think that you could supply that pretty easily from your main engine - maybe a 250 - 300 amp dedicated alternator through a small battery and properly sized inverter if they require AC. You could spin it up well in advance of needing it as it only requires 4 hp max, and I suspect less once at full speed, particularly in calm waters. Start up your stabilizer every time you leave the dock unless you're confident that it won't be needed.
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Old 12-13-2015, 01:17 PM   #104
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Gyro System

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John, many thanks for sharing all of this.

Your mention of the gyroscopic stabilizer piqued my interest. My first thought was that the power draw once spun up would be pretty low. I have an amateur interest in energy storage, and large flywheels on really good bearings don't typically need much energy to maintain speed. But I suspect that friction loss would increase in proportion to the stabilization required.

In any case, looking at the manufacturers data sheet it appears that the maximum power required is about 2.2 kw. I would think that you could supply that pretty easily from your main engine - maybe a 250 - 300 amp dedicated alternator through a small battery and properly sized inverter if they require AC. You could spin it up well in advance of needing it as it only requires 4 hp max, and I suspect less once at full speed, particularly in calm waters. Start up your stabilizer every time you leave the dock unless you're confident that it won't be needed.
Jeff, we thought the same as above and even had the west coast representative working with us to prove this out. After additional research we all concluded a generator is required for the size unit we needed on the this boat. Even if you could get the unit started and had a large battery bank you would be limited to around 6 hours of use until the unit drains the batteries down. Bottom line is the technology for a boat this size is just not there yet to run off an inverter. I'm sure in time they will get there.

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Old 12-19-2015, 10:47 AM   #105
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Week 6

This past week the yard completed glassing in the Longitudinal Stringers and started installation of the smaller transverse (left to right) stingers or ribs. Nothing to exciting (yet) but progress. I'm always surprised to see just how much larger / deeper a bare hull is compared to the finished product.

We decided to stay with Furuno Electronics for their reliability and plan to purchase the major components prior to the boats arrival to take advantage of a sale through March. Deciding on the new "touch screen" versus "conventional" display is our next tasking. I heard some concerns related to using the the touch screen in rough seas and being able find the display you want. Based on my limited experience with a windows phone I can see how this could be an issue but looking forward to trying out the screen.

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Old 12-19-2015, 11:45 AM   #106
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Even if you could get the unit started and had a large battery bank you would be limited to around 6 hours of use until the unit drains the batteries down. Bottom line is the technology for a boat this size is just not there yet to run off an inverter. I'm sure in time they will get there.

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John:

Jeff was not suggesting running the gyro motor off an inverter on batteries alone. He was suggesting installing a decent size alternator on your propulsion engine of maybe 200 amps at 24 volts or about 5KW, that could power the motor once it is up and running. The size of the batteries hooked up to it is irrelevant.

Some inverters, Mastervolt and Victron's I think, even sync with the generator power so that there is not even a millisecond of lost power when you switch over.

Such alternators are off the shelf units, simple and effective and the large invertert can run other A/C loads underway, with or without batteries.

That is what I would do if I was installing a gyro in my boat.


And someone said that increased friction would absorb power in a seaway as the gyro works. That is not it at all, although I am sure that bearings take a little more power when stressed, but not that much.


The real power is in the torque that the gyro exerts on the hull as it rolls. That torque times its moment arm represents real horsepower absorbed by the hull. But I doubt if it is anywhere near 5 KW.


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Old 12-19-2015, 12:14 PM   #107
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Thanks David. That was exactly what I was suggesting. It should be relatively easy to supply a couple of Kw of additional energy off the main engine to support this.

Any time I see someone suggest a need to run a generator while underway I question the need. Portable generators are quickly going to the DC -> inverter route, and it makes a lot of sense. I was scoping out what was required to run a/c while underway and it would be pretty easy to add generating capacity and run an appropriately sized inverter.
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Old 12-19-2015, 12:36 PM   #108
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Thanks David. That was exactly what I was suggesting. It should be relatively easy to supply a couple of Kw of additional energy off the main engine to support this.

Any time I see someone suggest a need to run a generator while underway I question the need. Portable generators are quickly going to the DC -> inverter route, and it makes a lot of sense. I was scoping out what was required to run a/c while underway and it would be pretty easy to add generating capacity and run an appropriately sized inverter.
The following summary was provided by the manufacture:

For the SK5, the gyro would need 2,000 watts to spool up (30-40 mins), then it would require 1,500 watts nominal, or around 55-65 amps @ 12 volt.
So with 2 to 3, 92AH, group 31 batteries and a battery charger, you are good to go for about 6+ hours, depending on the sea state.
(The SK3DC uses 45-55 amps, and can run for about 6 hours on two batteries)

While the approach (no generator) appears doable we would be pulling some high amperage with the balance of the boats systems added in. Since most if not all operators use a generator with the gyro we would be experimenting with an alternate approach and taking on a risk we were not ready for.

Great discussion!

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Old 12-19-2015, 12:49 PM   #109
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A/C Off Generator

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Thanks David. That was exactly what I was suggesting. It should be relatively easy to supply a couple of Kw of additional energy off the main engine to support this.

Any time I see someone suggest a need to run a generator while underway I question the need. Portable generators are quickly going to the DC -> inverter route, and it makes a lot of sense. I was scoping out what was required to run a/c while underway and it would be pretty easy to add generating capacity and run an appropriately sized inverter.
JEff, I'm curious to hear about running one A/C off the Inverter. We looked at doing this on the Nordhavn's with a Pro-Sine 2000 Inverter while underway. We had the Lugger engine with two generators and was warned not to try this for fear of frying the inverter. I struggle with this warning since we all run the A/C units off shore power. Thanks
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Old 12-19-2015, 12:53 PM   #110
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I'm not sure I understand the objection. Seems very straightforward to me. Size your main engine generator(s) and inverter for your maximum load underway, including the gyro, and maybe a/c if you want. No additional battery bank required unless you want to run with main engine off. Where is the risk? If you're really concerned have a dedicated system for your stabilizer, but I'm not sure I see the need.

I see the need for secondary generators going away in the future due to developments in inverter technology and capacity. There will always be a place for them in some situations, but it strikes me that many of the cases that existed ten years ago where a generator was required can now be alternatively addressed through the use of the propulsion motor.
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Old 12-19-2015, 01:02 PM   #111
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JEff, I'm curious to hear about running one A/C off the Inverter. We looked at doing this on the Nordhavn's with a Pro-Sine 2000 Inverter while underway. We had the Lugger engine with two generators and was warned not to try this for fear of frying the inverter. I struggle with this warning since we all run the A/C units off shore power. Thanks
The calculations are pretty simple. In my case I have a single 30 amp shore power connection @ 120v = 3.6 Kw. So if I put in a 4 Kw inverter I'll have more power available than I do when plugged in. 3.6 Kw is 300 amps at 12v, call it 350 to cover conversion loss. So if I increase my motor-driven generation by 350 amps I can do anything underway that I could do plugged in.

I should say that I have zero experience with using onboard generators, but I play with electric cars... Feel free to point out flaws in my thinking.

Edit to add that running a 350 amp alternator requires maybe 6-7 hp max from the motor. One hp is about 750 watts, not sure of conversion losses.
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Old 12-19-2015, 01:46 PM   #112
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John:

You seem to be strangely focused on the problems of running your gyro from batteries or the difficulties and/or reliability of a high output propulsion engine driven alternator.

Forget the batteries. No one is saying do that. And even though a high output alternator doesn't have perfect reliability, you always have your genset to fall back on.

Leece Neville as one manufacturer makes 200 amp, large frame alternators. Balmar (see balmar.net) is another that specializes in marine high output alternators that arguably have heavier windings, cooling and diodes. They make a 12V 264 amp alternator or almost 200A in 24V.

I am confused about your gyro running load. Is it 1,500 watts or 55-65 amps DC at 12 v. It can't be both. I suspect that you mean 24V.


I would install a high output alternator of at least 150 amps capacity at 24V since it is a long term, continuous load and also to leave some capacity for other uses.

I forget, what engine are you planning to install. Cummins or JD should be easy as they use the ubiquitous SAE J/80 mount for their Delco alternators. Or even better, keep your OEM alternator and add a second, large case high output one. It will take a custom fabricated mount to do this, but it gives you redundancy.

Finally the Prosine inverters are mickey mouse. Go with a heavy duty one such as made by Mastervolt, Magnum or Victron. A 3,000 watt inverter will run your gyro and most occasional AC loads like a microwave, hair dryer, etc.


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Old 12-19-2015, 05:39 PM   #113
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Leece Neville makes large frame alternators up to 500 amps. I have 2 LN 220 amp alternators as the second alternator, one on my charter boat, the other on my trawler. These alternators are designed for heavy continuous use on fire trucks ambulances, etc.

On my charter boat the second alternator charges an 8D battery used for starting the Cummins CT 300HP and powering an inverter that powers a 16,000 btu marine air conditioner. It takes about 140 amps 12 volt to run the AC unit, compressor running continuously. The primary alternator powers everything else and charges the house bank.

On the Trawler, the 2nd alternator (LN 220 amp) will run everything and charge the house bank. The primary alternator charges the start battery and powers the engine electronics only.

Both boats have a battery paralleling switch to tie both loads and batteries together in the event of an alternator failure.

The 220 amp alternator is capable of 3KW. The 500 amp is capable of 7KW. There are several sizes in between. The mounting is the same for all these alternators; the body just gets longer for higher amps. If I decide to go with a larger output alternator, it's just a matter of swapping provided you have adequate belt and battery cables.

Here are some pics from the trawler setup on my John Deere:

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Old 12-19-2015, 05:48 PM   #114
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We decided against a gyro stabilizer and having to run the generator did not influence our decision. The entire process of waiting for it to spool and the noise of continuous operation, especially if desired to be running at anchor are the factors that discouraged us. That plus the fact other stabilizers were more proven in actual use on the specific boat we were considering.
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Old 12-19-2015, 05:55 PM   #115
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Power Source

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John:


I am confused about your gyro running load. Is it 1,500 watts or 55-65 amps DC at 12 v. It can't be both. I suspect that you mean 24V.

David
Davis & everyone, thank you for the responses and input. Good catch on the manufactures quote, I believe the system requires 24V. We selected the Cummins 380hp engine thus a larger alternator should not be an issue. Matching the inverter to the load is also doable which make me wonder why the factory rep of the Gyro stabilizer advised (after weeks of discussion) not to go this route. Its water under the hull now since we made our decision on this boat to keep things simple and would likely lean towards Trac Active Fin stabilizers if we were to go down this road again on larger boat. Great discussion.

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Old 12-19-2015, 06:20 PM   #116
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Boarding & Aft Cockpit

Our last post focused on the Pilothouse and how important that part of the boat is too us. Today's post will focus on the aft deck and boarding the boat. If we learned one thing from living aboard it was the significance easy boarding had on the entire experience. We are fortunate in southern California where all the marinas we stay at have floating docks which provide equal level between the dock and boat. I can remember growing up on the east coast and having to deal with fixed docks, it made for some interesting times during maximum high and low tides. It was a good thing I was a teenager back then.

For us boarding doors on both sides (port and starboard) is a "must have" to accommodate docking on either side. Side doors get significantly more usage then the transom door while at a dock. The size of the doors is equally important as is their depth or cut out. On our N40's we found the doors to be a little small and not cut to the floor like on the larger models. Not having the door cut close to the floor results in a lip which can be dangerous if you use it as a step (its too narrow for good footing). The Helmsman 38PH offers large boarding doors cut low and the cost to add the optional starboard side door is minimum. The transom door is still handy when boarding the dingy, kayak or other water toys and when loading provisions from the dingy. Bottom line is having access doors on all three sides is a low cost but must have option for us.

Having a good size aft deck is another important aspect of any boat that should not be overlooked. When you recognize the aft deck is actually an extension of the salon and is used for so many different purposes "bigger is better". Again we learned from previous boats that we wanted an area large enough for two nice chairs and a table while still being able to enter and exit the salon. The larger cockpit also provides for a larger lazeret below. The Helmsman 38PH offers us more then enough room and with the upper deck overhang it would be easy to enclose this area making it a year round entertaining area. That's all for today.

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Old 12-19-2015, 06:26 PM   #117
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The Helmsman 38PH offers us more then enough room and with the upper deck overhang it would be easy to enclose this area making it a year round entertaining area. That's all for today.

John
Do they offer the enclosure or is that something you'll have to get aftermarket?
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Old 12-19-2015, 06:36 PM   #118
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Do they offer the enclosure or is that something you'll have to get aftermarket?
Great question. Scott is very accommodating and if asked he would talk with the yard on a new build. I have seen a very nice aftermarket enclosure on a 38PH so it is definitely something you could add. The cost of labor in US would make the decision to have the yard add it may be sense if you know you will need it.

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Old 12-19-2015, 06:50 PM   #119
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Boarding gates on the boat's side sound very desirable. With my poor balance, stepping on a swim step for a stern boarding isn't pleasant. In my case, it's a matter of stepping over the gunwale onto the near-dock-level deck that works.
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Old 12-19-2015, 07:15 PM   #120
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We decided against a gyro stabilizer and having to run the generator did not influence our decision. The entire process of waiting for it to spool and the noise of continuous operation, especially if desired to be running at anchor are the factors that discouraged us. [...]
Sorry if this is a dumb question, but don't the alternative stabilization systems only work when underway?
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