Installing a bilge pump in Mac 25

[Catigale]

Walt - something not right in your calculation

32 Amp hours * 12 volt nominal is 384 Watt hours used

so you would need a 65 Watt panel on at full efficiency for 6 hours to recover that energy.....and in practice a 130 Watt panel at a typical 1/2 efficiency

[walt]

You could be right, Ill double check a little later. It takes a lot of solar panel area to supply power real time but my numbers would have would have assumed that I only use the boat occasionally but the panel is charging "full time". Ie, the panel is charging for 7 days per week but Im only using the boat for 5 or 6 hours per week.

Cant check now but I will later. Ive only made about 30 million mistakes in the past so this would not be the first.

[johnnyonspot]

Back to your original premise ... the bilge pump. Most Mac owners take the view that Roger didn't drill any holes below the waterline, they're not going to either. Without an underwater fitting to fail, how can the boat take water? If it's taking water topsides, that should be very slow and easy to find and fix. In the unlikely event a split hull is admitting water, then your bilge pump, battery and solar charger ...
all 3 will be peeing upstream.

I agree. That's what I meant earlier when I suggested I was being paranoid. The only time I have ever noticed water in my bilge was just after I had run aground while sailing down wind toward a lee shore in order to minimize the rolling of the boat while my 2 crew were reconnecting one of the port shrouds that had come unscrewed and was swinging in the wind. When we ran aground, well short of shore, the boat was heeled over quite a bit until we dropped the sails and cranked up the keel and motored out of there. I have since not noticed any further water in the bilge; how it got in that day I still do not really know.

[Frank C]

I guess that heavy keel suspension & trunk is a bit "higher risk" for leaking than anything in a Powersailer's hull. Since you went aground, I suppose there's a slight chance of a split hull. Check closely at the base of the trunk, and at the pivot bolt.

[johnnyonspot]

I sailed it 2-3 times after the grounding and the bilge remained dryer than a popcorn..., ahem, dryer than a bone, so I presume there are no water tight integrity issues with the hull. However, my checklist for spring includes dropping the keel, sanding rust off, priming, painting, and inspecting both the pivot pin and cable. So I should be able to easily inspect the trunk at that time.

It was not much water in the bilge that day. I wonder what the chances are it came in up through the tube in which the cable runs, either all the way up, or out through the spot where the tube comes through the hull.

BTW, thanks for the DVD; have not had time to watch yet, however.


RE bilge pump, I found a good thread here: http://macgregorsailors.com/phpBB/viewt ... es+led+aft

Rather than run the water out the gunwhale, I think it would work better, at least in my Mac 25, to run it out the stern, higher up at Chip's height.

[walt]

hello Catigale,

I checked my numbers and they are OK. Just as a double check, Ill use your watts method..

I said that in one weeks time, I used 32 amp hours = approximately 384 watt hours (using 12 volts which is a little on the low side).

With the 19 watt panel and charging 6 hours per day for 7 days (ie, 42 hours), the power generated by the panel is:

19 watts*42 hours / 2 derating = 399 watt hours. Ie, during the week, the panel generated 399 watt hours and I used 384. So both methods give close results (if the voltage you used to calculate power was 12.46 volts, the results would be identical.

[Catigale]

My bad - I thought the 384 Watt hours was daily energy consumption, but you have 7 days to recover it, so the smaller panel works out..