Cracked cuddy floor

[hectoretc]

The other reason I hope that your resin is epoxy is that it doesn't shrink on curing like polyester will...

If I haven't been using epoxy before, I will for this... need to read the can to see what it is, just picked it up at Home Depot a couple months ago (probably "Bondo brand", so I suspect it's probably polyester).

Thanks for that info too...

[GreenLake]

Epoxy comes in two parts, typical mixing ratios are simple integers by volume: 1:1, 1:2 etc, depending on the brand.

Polyester is catalyzed. One large container and a small one with the catalyst. Something like a few drops / ounce.

So you don't need to read the fine print to know what you have.

While new hulls are laminated with polyester (for cost reason) this is not the best solution for repairs.

Epoxy bonds better to already cured material, does not shrink, and requires less aggressive ventilation. (Also less sensitive to flex, but deteriorates if exposed for months on end to UV).

Popular epoxy brands (for boat repair) are West System and System Three. (Both companies have manuals on their web sites).

Epoxy must be mixed precisely and very thoroughly and usually requires 65F or higher to cure. (Polyester simply hardens faster if you use a bit more catalyst - the wrong mixture with Epoxy will not cure, that goes for any under-stirred portions of the mix - such as near the bottom).

Since you buy things in 55 gal drums - be aware that epoxy heats up after mixing - work in small batches (size of a paper coffee cup or less) and/or pour the mixture into a tray so it can cool. Overheating epoxy can catch fire.

If you store epoxy resin at low temperatures, it will crystallize - you'll need to soak it in hot water before using it - so best store in a cozy place indoors.

Wear gloves at all times and have plenty of vinegar to clean up spills and drips of uncured epoxy (but don't rinse mixing containers, even traces of vinegar will interfere with proper curing - you'll need a near infinite supply of disposables...)

[talbot]

I'm contemplating the same type of modification, but with the battery box just forward of the mast. I know, farther from the center of effort, but also out of the way of the CB control lines and storage spaces.

Question: How much of a "receptacle" are we talking about? I considered building a fiberglass box with the battery box as a mold, but then I thought, if I'm just cutting a hole to accept one #24 battery box, couldn't the box itself be the receptacle? I was thinking I could cut the opening to just fit, fashion a flange to pin the battery box sides tight to the edges of the hole, seal every seam with silicone, and call it good. Thoughts?

[GreenLake]

You are (may be?) legally required to have the battery in a box and secured where it can't tip, leak or fall out of the boat. So you'll need a complete box in any case.

I find it easier to lift battery boxes with two hands than batteries (if they even have strap). But then I remove my batteries frequently.

So that all depends.

If I was going to do what you suggested, I'd first test the plastic of the box for deformation when heated. If you can deform it easily when hot, then I'd cut the box 2-3" taller than needed, and bend over the last 2-3" of each side and rest it on the cuddy floor. It'd fix each with pop-rivets, easy to do and will hold better on plastic than glue.

Some goop to make a seal, and, rough and ready. Two flat strap holders screwed (better through bolted) on either side to take a strap-down for your battery so that it will survive a capsize in place.

I'd probably still go for a proper battery well from laminate.

[hectoretc]

I'm contemplating the same type of modification, but with the battery box just forward of the mast.

You probably are already aware of the real estate under the forward part of the mast step but "just in case", be conscious of the following.

[thumb=1158] (this picture from Roger's book)
Immediately under the mast step is a pedestal that supports the mast weight, and there is a (what I presume to be) piece of wood, fiberglass laminate, or some other inert material between that pedestal and the cuddy floor (sole) so you will want to allow a couple inches between your cutout and the mast. Also, be aware that the forward bilge bulkhead (under the cuddy sole) is well aft of the bulkhead above the cuddy sole. .
[thumb=1088]
The discoloration in this picture is a crack repair that is "on" the under floor bulkhead. I don't have the exact measurements but will get them next time I get to my boat and will update this post. It looks to be 18-24" forward of the mast though so there is plenty of room. Depends on if you cut your hole to install the battery box wide or long in the cuddy.
Assuming you would put it closer to the mast trying to get the weight as far back as possible, best recommendation might be to mark a pencil line around your intended box location, the using a saw cut a hole close to the most forward line of the box big enough to stick your hand through, then reach in and insure the your intended cuts won't interfere with the mast support. If you find you are too far back, you can then move your box cut out forward a few inches to miss the mast support, etc.

Just another thought to toss on the pile... -Scott

[talbot]

Thanks. My thinking is evolving. I measured the height of the CB pennant exit inside the cuddy and it looks like, if the battery box goes into the floor about 7", the pennant will clear the lid of the box. Which means I could join the crowd and also put my box aft of the mast. (Pennant would go parallel to the floor to a block on the mast section, instead of down to the floor, as it does now.)

Back to the battery box: I want to leave the box intact--if anything, stronger than it was off-the-shelf. I was going to attach an external flange to the box (not sure how, but I will). The box will rest on the bottom and be screwed and sealed at the edges to the cuddy floor at the flange. Ideally, the 40# of weight will be shared between keelson and cuddy floor. I was thinking I would laminate additional fiberglass laminate under the box, an area I gather often needs to be repaired anyway. The top will come on and off as it usually does for accessing the battery.

My idea is that the battery box should do double duty: It serves as the battery well, and, when its flange is unscrewed, provides a very big inspection port that allows access to the CB trunk, mast footing, and that screwdriver I dropped in 2007.

[jdoorly]

2 thoughts: First puting the battery in front of the mast adds length to motor cables and therefore increases the cable's voltage drop which decreases top speed and range on a trolling motor. No trolling motor? Don't sweat it unless you, like me, have an auto-helm that is voltage sensitive.

Second don't put a battery directly on the hull. Put an inch or more of distance between the battery and water (I used wood). Apparently, water near a battery can discharge the battery by means of induced currents. Also, don't rest batteries on concrete for long, same reason.

[GreenLake]

Hmm. Have to disagree a bit here.

A battery is a DC device. For the chemistry to work out, the electrons have to physically move between anode and cathode. While an AC current can move power across short distances of dielectric (think capacitor) a DC current stops and electrons stop moving as soon as the voltage in the capacitor is the same and opposite of the driving DC voltage. A good capacitor has huge surfaces and very narrow gaps, unlike a battery near water. (If you set a bare battery in water, it may help keep salt and acid crystals moist on the battery body, creating a path for weak discharge currents between the poles. Plastic battery boxes do a good job keeping water out...)

As for the relation between concrete and batteries, it's widely considered an urban legend. I still wouldn't store batteries on concrete unprotected - in case of a major leak, I'd have a memorable hole in the floor.

Because of the possibility of leaks, you should always have a box for your batteries, whether built-in, or one of the portable plastic jobs. And you need to strap down your battery. For a setup like the DSII, for those that don't want to construct a battery box, building a battery well seems like a good alternative.

On my DS1 I don't bother with that and simply rest my battery boxes on the floor in front of the benches, secured in place with straps. The cuddy floor is a dedicated "passenger compartment" and I don't take my batteries with me every time I go out - less than half the time, I would say -- so keeping them where I can access them when the boat is on the trailer is a huge plus. In between, the batteries in their boxes sit, you guessed it, on the concrete floor in my garage, where they get recharged about every other month, which seems to work out fine.

I'm surprised your autopilot is so sensitive, but if it's just a trolling motor, I doubt that +/- 2ft will make an observable difference. Adding 16% of the distance should increase the total voltage drop in the cables by 16%, or 1/6th. If you've kept your voltage drop small to begin with, this 1/6th shouldn't have any observable effects.

I used to run my motor by moving a battery back, that was before I added a cable run. I've tried it, and I can't see the difference. There's too much "noise" in the real world - different wave action, wind direction, strength, differences in the trim of the boat, etc. for any small change like that to "show". (OK, perhaps if you had trolling motor races between otherwise strictly comparable boats.).

Anyway, sorry for being so "disagreeable" today.

[talbot]

Let me make sure I understand jdoorly: Are you saying the battery can discharge through the plastic battery box into the bilge water? Even if the battery box itself is dry?

I'll confess I don't understand the DC current argument; seems to me the sloshing water in my bilge would be an . . . um, fluid situation, where voltage differential between battery and bilge might vary. But I did look up the concrete floor question. Interstate Battery says that it was true when batteries were encased in hard rubber. No battery on the market now should leak electrons through its plastic case.

For me, the whole problem with the battery is weight. Next to me, it is the heaviest single thing on the boat. I hope to use it rarely, and I want it to cause minimum interference with sailing. The whole reason to drop it through the floor is to get its 40# as low as possible. So I'm loathe to lift it up any more than is necessary to reinforce the keelson and keep the thing from falling through the hull.

[GreenLake]

To charge or discharge a battery requires a set of chemical reactions(there was this other battery thread here where someone posted a link to a nice summary of the chemistry). If the electrons cannot migrate, the chemical reactions cannot take place.

In AC current, the electrons slosh back and forth, but never get very far. You can insert an isolator, but with the right geometry (flat plates closely spaced) one side will induce sloshing motion in the other and then the AC behaves as if the isolator wasn't present.

In DC current, that doesn't work, because no electrons would get across the barrier. So, as you write, as long as your box (and the battery case) is an insulator, who cares which way the bilge water sloshes - the circuit will not be completed and no electrons will actually flow the distance.

The battery body itself is often contaminated by traces dried acid or salts and this can lead to a very slow discharge of the battery, as these materials will form a conducting path when moist. Cleaning your battery and using a battery box will help.

As to placement, I'll go out on a limb and claim that moving them forward by 2ft is something that you might be able to tell in trim, but raising them by 1-2" is probably in the noise. I would make sure that they are not placed such that they can allow bilge water to collect in front of them - any small amount of space underneath or near the keelson should take care of that, though. That's a question of drainage and not of electrics.

My DS1 sits fairly low in the water in the back, even when nobody is on board and no batteries are in the boat. Given that, I'm placing them too far back for optimal trim, but I load/unload them from the boat each time I go out (unless I leave them at home). So that was the point I needed to optimize.

[jdoorly]

All I can say in defense is that last year I did some extensive internet searching on the care and feeding of batteries. I can't say where I read it but I definitely read it and in my attempt to rectify my battery problems I obeyed it. I also have a background in electronics and choked at first on the concept, but then there are zillions of things I don't understand that appear to be true. My cordless electric drill manual says to take the battery out when not using the drill or the battery will discharge and lose charging life. I didn't do that and just had to replace multiple batteries. The batteries are 18 volts DC.

So, talbot, I'm not saying that batteries can discharge due to sitting in water, or being a short distance from water, or being on concrete, somebody else said it, I just believed it. Sorry I can't provide the footnote.

So, Greenlake, I said an apparently stupid thing and should get called out on it. I should have referenced a source, I was just lazy.

[GreenLake]

jdoorly - your contributions are usually rather well founded particularly when it comes to an understanding of the mechanical properties of and possible loads on your many interesting designs. So this one, seemingly repeating an urban legend, stuck out, and I couldn't resist commenting.

When it comes to batteries in particular, a large amount of information that's out on the internet appears to represent rather shallow understanding of the subject - and to some extent, I'm including myself here. (I had occasion to speak to an electric propulsion expert a while ago, and his perspective and depth of knowledge was eye-opening)

I'm still in the process of sifting what seems to be reliable information and what is merely unsubstantiated repetition. I'm on my fourth or fifth trolling motor battery, so I would quality my own direct experience as "limited". I treated mine as described and have been experiencing what I believe are reasonable life-cycles in terms of years (5-7), but I've not really stressed the batteries to their limits in terms of the number of charging cycles.

I use them for backup propulsion and that means, they mostly serve in "stand-by" mode. For a number of years, I've had one of my batteries sit outside (on a deck, not on-deck) without observable difference to its partner, which spent the same time on the concrete floor of my garage. For what it's worth. There are many prescriptions about regular maintenance charging which I follow only on a "if remembered" level, but apparently whatever I did proved sufficient.

That said, I've had one battery (that had reached the end of its life) die on me on the water without warning, and since then I'm always taking two. Before, I probably ended up discharging the single battery a bit too deeply on occasion, with two, I end up swapping batteries sooner and that seems to help them live longer as well.

I've also switched brands over time, and that seems to have made some difference in durability.

Getting back to the question of "footnotes". If this was an "academic" forum, I wouldn't post here. That said, if you find me writing something that you find hard to swallow, please don't hesitate to ask me why I believe in that particular statement. At best I'll be able to give substantiation, at worst, I'll learn something about my own hidden assumptions.