Boat lift options?

[nola mike]

Local drama, my boat ramp is closed for at least the season. All the construction is bananas around here, but the guy doing a pier next door agreed to drive 4 pilings for me while he's on this job. The pilings are going to be standalone with a lift that I'll be buying/installing. For a few reasons, I don't want to run AC power down there. I'm looking at a couple of lift options, either overhead beam (2 beams running parallel to the boat) or piling mounted standalone (magnum brand).
1. Anybody done this, and any suppliers that you'd recommend?
2. Motors: NOBODY wants to deal with DC lifts, which I suppose should tell me something. My other options are to have a generator down there to run AC motors (yuck) or have an inverter to drive AC motors. Both of those options seem like bad ideas. The lifts all use standard 56 frame motors, so I should be able to source them pretty easily if the company doesn't supply them.

This stuff is not my forte...so anything that I'm missing please let me know. But please no, "you're better off running power down there" comments. It ain't happening.

 

[dingbat]

2. Motors: NOBODY wants to deal with DC lifts, which I suppose should tell me something.

Depending on what size lift your looking at a demand of at least 3.3 kW.
That's a heck of load to power with a DC power source.

Nothing overhead unless you have a boat house setup. Two overhead mounting beams are the perfect "rooster" which to defecate on the boat.

Locally, Magnum and Golden are popular.

 

[nola mike]

Depending on what size lift your looking at a demand of at least 3.3 kW.
That's a heck of load to power with a DC power source.

Nothing overhead unless you have a boat house setup. Two overhead mounting beams are the perfect "rooster" which to defecate on the boat.

Locally, Magnum and Golden are popular.

The AC motors are 3/4 hp, which is ~550 watts?
Yeah, I'd like to avoid the overheads, but if it's a $3k difference not worth it. The beams wouldn't be over the boat anyways, and we don't have too much of a bird problem here. The beams would also allow me to run some sort of canopy in between for cover.

 

[JimS123]

Been there, done that with the "can't run power thing". Also, with the DC thing.

AC is the only answer. A small Honda portable inverter genny is the answer. Quiet and dependable. Store it in a lockable dock box right at the site.

I would imagine your usage would be quite small, so possibly a china champion at half price may fit your needs.

 

[nola mike]

Been there, done that with the "can't run power thing". Also, with the DC thing.

AC is the only answer. A small Honda portable inverter genny is the answer. Quiet and dependable. Store it in a lockable dock box right at the site.

I would imagine your usage would be quite small, so possibly a china champion at half price may fit your needs.

So what were the issues you had with DC?

 

[dingbat]

The AC motors are 3/4 hp, which is ~550 watts?

That's "work".......motors are nowhere close to being 100% efficient.

3/4 HP, 1 phase AC Motor FLA is 13.8A at 120 VAC.

You have two motors.... 27.6A x 120VAC - 3,312 Watts

https://www.magnumlift.com/pilespac/Magnum%2010K.pdf

 

[JimS123]

So what were the issues you had with DC?

My "issue" is that the batteries always needed charging. So, I ended up with a genny AND a battery charger. Otherwise, its taking them out and charging them at the house.
Either way is a PITA.

 

[nola mike]

My "issue" is that the batteries always needed charging. So, I ended up with a genny AND a battery charger. Otherwise, its taking them out and charging them at the house.
Either way is a PITA.

I'm fine with that, I plan on putting in a solar charger. I also do have power to the shore, but it's at least 100' of 12/2 UF wire, so plenty to charge batteries but not nearly enough for a lift. As long as it wasn't an issue specifically related to the lift + DC motors, I'm OK.

 

[nola mike]

OK, doing a bit more research, and this definitely seems doable. The simpler lift systems out there use pulley driven flat gear plates. Old school, simple. Any motor can drive them with a belt. I found a lift for around $3k that is rated for 6k pounds. 2 motors, and lift speed is 3.5'/min. They come with 2 3/4 hp motors. Looking at 12v DC motors, they draw ~60 amps (not sure if this is load dependent). So for my 10' lift height I'm looking at about 10 cycles nominal max for a 90 aH battery, or 5-6 cycles if I get 50% of the rated capacity, and less than that if I want to keep a healthy battery. That's cutting it close, but I'll rarely if ever use the full lift height more than 2 cycles/day. Even a 100W solar panel will bring me back to full charge after 3-4 hours per cycle.

Not sure if my math is right or if I'm making any assumptions that I shouldn't be, but I've tried to be conservative.

So the additional cost of solar/DC would be:
1. $2-300 or so for motor upgrade
2. $1-200 for each 100W solar kit (2 needed)
3. $3-400 for batteries, maybe add an extra and a battery switch for emergencies. Of course, the wild card is how long the batteries will last.

So about ~1k extra for the solar DC setup. My buddy just had 30 amp service run to his pier and it cost $4500, + $200 permit (plus who knows when I could get it done).

 

[JimS123]

OK, doing a bit more research, and this definitely seems doable. The simpler lift systems out there use pulley driven flat gear plates. Old school, simple. Any motor can drive them with a belt. I found a lift for around $3k that is rated for 6k pounds. 2 motors, and lift speed is 3.5'/min. They come with 2 3/4 hp motors. Looking at 12v DC motors, they draw ~60 amps (not sure if this is load dependent). So for my 10' lift height I'm looking at about 10 cycles nominal max for a 90 aH battery, or 5-6 cycles if I get 50% of the rated capacity, and less than that if I want to keep a healthy battery. That's cutting it close, but I'll rarely if ever use the full lift height more than 2 cycles/day. Even a 100W solar panel will bring me back to full charge after 3-4 hours per cycle.

Not sure if my math is right or if I'm making any assumptions that I shouldn't be, but I've tried to be conservative.

So the additional cost of solar/DC would be:
1. $2-300 or so for motor upgrade
2. $1-200 for each 100W solar kit (2 needed)
3. $3-400 for batteries, maybe add an extra and a battery switch for emergencies. Of course, the wild card is how long the batteries will last.

So about ~1k extra for the solar DC setup. My buddy just had 30 amp service run to his pier and it cost $4500, + $200 permit (plus who knows when I could get it done).

I have solar on my mountain top RV. Current pricing for a "system" with a single 100W panel is $309. You need a good quality controller or you'll fry the battery. The $100 kits are not too efficient.

Even at that, depending on the depth of discharge, 3-4 hours might be a stretch.

 

[cptbill]

I have a 6500 watt portable gen that we use for power outages, I also put it in the back of the truck and take it to the lot we store the boat at for hurricanes and maintenance. Anyway when its hooked up to the house at will run my lift with no problem, I put wheels on the rear of the gen so it's easy to pull around if need be. It was not that expensive(Harbor Freight) and I seem to use it more for things other than power outages and well it's just nice to have a back up

 

[JASinIL2006]

We bought a Renogy 100w kit for our cabin, and it has a nice controller and everything you need. They have 200w kits in the $300-400 range.

 

[nola mike]

I think I'm going to do the dc motors and size the panels after I test the actual time the motors run and how many amps they draw. I'm also considering whether it's better to run/charge 2 batteries in parallel or to have each motor have its own system. Thinking the latter, since amp draw will be less so will lose less battery capacity to internal resistance

 

[cptbill]

I would think the first option would be better. Then you don't have to worry about voltage differences and the motors possibly turning at different speeds

 

[nola mike]

Interesting. Didn't think of that

 

[roscoe]

Dang, I remember when we used to lift grandpas boat by turning a large hand wheel. It worked every time.

 

[nola mike]

Dang, I remember when we used to lift grandpas boat by turning a large hand wheel. It worked every time.

Definitely thought about that, and wanted to do it. Until I realized that those motors turn at 1800 rpm and still only raise it 3'/minute

 

[nola mike]

OK, getting a little closer. Got the pilings driven, waiting on the lift (I'm told it will ship this week...)

I've decided to do 2 separate systems, each with its own battery and control. I want to minimize the amperage through the switches and batteries. I'm going to decide on the solar options after I assess how much I'll need.

I'm going to use these motors, which should work. 30A max draw.

I am having a bit of difficulty figuring out the switching and wiring. I can't seem to find many options for a 30a switch, so I'm thinking the better option is to put 1 DPDT relay and DPDT switch on each side. A bit more complex wiring, but that would also allow me to use basically any type of control switch (keyed, maintained, momentary), and allow me to mount the switch far from the battery/motor. Also would allow me to easily reverse the motors. Here's the relay I was looking at.

I clearly don't have a lot of experience with this, and still can't find an example of a system I can copy.

Any thoughts appreciated...

 

[nola mike]

Alright, so we're live! I discovered that a lot of my parts (specifically that reversing relay) are all over the place for atv winches. The problem with most of the things I looked at was that there wasn't an easy way to reverse the polarity to the motors. It would have required multiple relays and much more complicated writing. So I got reversing relays driven by 2 SPDT switches. Completely separate system for each lift motor. 100 ah batteries. The lift runs at 2'/min, and I need about 6' of lift to get it safely out at low tide. So 3 minutes at 30 amps, or 1.5 ah. I ended up with a 50w solar panel on each side with a listed max output of 3 amps. When I tested at 5p today I was getting 1.8a. Even at that rate, that's all of the lifting I could possibly need for a day, plus the huge reserve of the battery (which seems oversized at this point). I don't know how much current the motors draw when lowering, but presumably a good but less. Anyway, so far so good. I'll update even if nobody is interested, since I couldn't find any resources about this on the interwebs..

 

[Scott06]

Alright, so we're live! I discovered that a lot of my parts (specifically that reversing relay) are all over the place for atv winches. The problem with most of the things I looked at was that there wasn't an easy way to reverse the polarity to the motors. It would have required multiple relays and much more complicated writing. So I got reversing relays driven by 2 SPDT switches. Completely separate system for each lift motor. 100 ah batteries. The lift runs at 2'/min, and I need about 6' of lift to get it safely out at low tide. So 3 minutes at 30 amps, or 1.5 ah. I ended up with a 50w solar panel on each side with a listed max output of 3 amps. When I tested at 5p today I was getting 1.8a. Even at that rate, that's all of the lifting I could possibly need for a day, plus the huge reserve of the battery (which seems oversized at this point). I don't know how much current the motors draw when lowering, but presumably a good but less. Anyway, so far so good. I'll update even if nobody is interested, since I couldn't find any resources about this on the interwebs..
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Nice work. I think you probably have way more battery capacity than needed. I converted my R&G vertical aluminum lift to dc power by taking iff the hand crank and using a 12 vdc winch like offroaders put on their front bumper. Use a group 31 deep cycle battery and 7 watt solar charger. Use the hoist 3-4 times a day no issue.

let us know how you make out