Lewmar 700 Pro (horizontal) windlass install note (hole cut)

[jkidd]

[Sunbeam]

Of course I had to lie awake last night thinking about windlass forces. Not because I think it really matters in the case of our size boats (I think just non-cupping fender washers and epoxy annuli would be more than fine), but just because my mind enjoys thinking about things and getting how they work.

So I envisioned myself standing on deck, facing forward, and pulling in the anchor. Heels dig in, toes lift up. If the anchor were pulling back (and winning), then I could imagine my toes digging in, and my heels lifting. Plus probably mostly a force trying to drag me straight to the roller (i.e. shear force). Especially if I were only ~6" tall like the windlass.

Of course the lower skin of a cored construction is usually thinner, and too, the bottom of the windlass has a somewhat larger footprint on the top deck than the nuts on the overhead, but it made me think that the windlass might be just as likely to "dig" into the top of the deck as lift up on the bottom (?) And the main force is probably trying to pull the fasteners forward (sideways) toward the bow roller and not up very much at all. So, really, I'm not sure that in this case a big backing plate is really doing too much (not that it hurts).

Too, the backing plate does help spread load, but on our boats, there are no deck beams, nor an anchor locker bulkhead tabbed from hull to deck, so really any stress on the foredeck, even when "spread out" is still all on the foredeck, theoretically (they say) trying to pull it off the hull. It's not like our backing blocks are tied over into the topsides. So as long as there is no chance that fender washers would pull up into the bottom skin (and it seems like there would really not be much force pulling up), then... the backing plate is really sort of just "because." If the load spreading is not necessary, and the backing plate cannot actually transfer the force to any other component. I say this as a big proponent of backing plates, who would "never" "just" use fender washers (but is thinking they are probably just fine, especially on our boats). I just felt like thinking about my assumptions regarding backing plates last night.

I still do think that backing blocks on the cleats are useful, and I'm adding them. I've had times at odd docks or tides or whatever where there WAS upward force on the cleats. And you can motor in and throw a line out to "catch" you... that's got to be a lot of force (much more than the windlass, I would think?). Actually, if anything, I might be tempted to put a "backing plate" on TOP of the deck, to keep the windlass from digging into the gelcoat (and perhaps level it somewhat). Don't think I will, as I have not seen any evidence of issues with them mounted straight to the deck, but this is what started my musing... if a backing plate were necessary below, then why not on top too?

Okay, major ramble, and if anyone who understands physics (and likes explaining it to lay people) wants to chime in, by all means! As I said, I'm not actually "worried" about this in a practical sense, but I like to think about things and how they work, and I couldn't get to sleep Ironically, half of you reading probably are, now

[Sunbeam]

Figured I had better put this in a separate entry. Since we have added electrical talk to this thread, I would like to ask about house vs. start bank for the windlass. I had been thinking (automatically) that I would hook up to the house bank, but then I read about someone running the windlass from the start bank instead (to always be used with the engine running). Hmm, maybe that makes a lot of sense? Say you are on the hook for a couple of days or more, and your house bank is down to 70% SOC. You fire up the engine and get ready to go, and then use the windlass.... on a partially "tired out" battery. And if I remember this correctly, if one has an ACR, the start battery would still be "isolated" from the engine and start battery (I forget when the relay closes again, but it would have been open the whole time at anchor). So maybe it is better to have the windlass drawing right from the totally fresh (and definitely connected to the engine charging) house battery?

I have a "cruising style" system, with a smaller, dedicated start battery, and a larger, dedicated house battery (bank), so... does this change things? Or with the engine running, does it not really matter that my start battery is smaller? (It has 580 CCA, but I'm not sure from looking at the specs how many amp hours it has in the way a house battery does, or if that matters for this application.)

Interested in what others think about which battery to attach the windlass to. Specs say it draws 35 amps.

[thataway]

First addressing your "physics" question. You should never be loading the windlass to more than a few hundred pounds. It is not built for that --yes theoretically it will pull 700 lbs. But why is the rule, you never pull the boat to the anchor, you break the anchor out with the boat, and use the windlass to hoist the anchor and chain up to the deck?

Deck skin. You should have put the epoxy between the two skins of the deck. This makes the area in compression safer, because you are pulling mostly on the center part which is agains the core of epoxy, bonded to the outer skins. When I had a two speed windlass which would really pull 3500 lbs, then I had a huge 3/8" aluminum plate under a large portion of deck. But that is with a boat many fold heavier and with other resistances higher than the C Dory.

You are correct, that much of the pull is forward, but also lifting upward. The windlass case takes the downward load--and is fairly broad, and strong forward.

House ve engine start. I in the C Dory's I have used house and engine start of equal size for a number of reasons. However, you should always have the engine going when you are pulling the anchor. You gave one good reason--you have a partially discharged house battery when you have been at anchor. The other is that the voltage will be higher, because of the alternator output, and thus there will be an adequate voltage presented to the windlass motor.

[Sunbeam]

[thataway]

Ref start battery. Not all of the boats have VSR, If the boat had a VSR, it may or may not have closed--that is an unknown--but if you really want, you have the Victron Gauge to monitor the voltage of both batteries (at least my Link allows 2 battery voltages to be monitored).

If you have depleted the start battery with an engine start--then there is something either wrong with the battery size, condition or the engine. A 150 +/- amp load for a few seconds should not deplete a battery, if sufficient size.

The engine should have been warmed up for at least a couple of minutes before you put in it gear.

[Sunbeam]

So it sounds like it would be fine (and perhaps even a good thing) to hook up the windlass to the start battery, even though it is a smaller battery (why I wondered). This would certainly simplify things if I do move the house bank, and even if I don't, it would also avoid any potential issue if I had run my house battery down to close to 50% over a longer period at anchor.

I would already have started the engine before putting any load on the start battery with the windlass. After all, it's not like I'm going to up anchor and sail to the next spot So far I have never had to do anything but basically turn the key to start my engine, so it's not like I am cranking for minutes like a car in January. Essentially, the start battery's only job (unless I hook the windlass up to it) is to start the engine; otherwise it is sacred and untouched

My battery monitor only monitors one bank, and that is the house bank. There is a version that monitors voltage only on a second bank, but I did not purchase that one.