28 Cruiser

[Scott Dunsworth]

We are about there.

[Scott Dunsworth]

When I build the ice box I am planing to use a minimum of four inch's of foam insulation, also a drain as Peter has done on his P28. I also would to like to add a refrigeration plate in the box also. My question is when a manufacturer says the unit uses 1.5 to 2.5 amps, does this mean continually, on average or just when running? We are planing to have 120 watts of solar panels with 3 to 4 batteries in the house bank with a separate starting battery. My way of thinking is with a block of ice and the cool plate that it just wouldn't require that much power to always have a cold box. But if they use 2.5 amps continually it would be out of the question.

As for the rest of the electrical system we will use only leds and power saving systems. The small hot water heater will be 110, so it will be only used where we can plug up. My wife has questioned me about the built in marine air conditioning systems also. Which I have had to tell her I know nothing about those.

Can anyone recommend a good boat wiring book that doesn't get to deep into electric theory, just the nuts and bolts of it?

Scott

[Ray Frechette Jr]

Well, I just gave a course at Wooden Boat school called "Intro to marine electrical systems".

The subtitle of the course that I used in class was "101 ways to burn down or sink your boat and electrocute people you love"

Electrical systems on board boats get very expensive very quick.

If you are going to do it , do it right. Wing's book lays out the appropriate ABYC recommendations to do it safe.

You really do need to understand at least a bit of theory too.

Charlie Wings Book Understanding Boat electrical systems is a must have.

Also Nigel Calders book on mechanical and electrical systems is a good read too.

The 1.5-2.5 range likely refers to start up loads and continuous run loads. IE a compressor has higher startup loads on the electrical system than it takes to keep the compressor running steady state.

The better you insulate and construct your ice box the less amp hours you will consume underway.

Where you use this, and how often goes a long way to making decisions on how you want to go.

Recommendations to a liveaboard in the Carribean would be far different than to someone putzing around in great lakes a few weeks per year.

Both books well worth investing time and money into.

OK, DC refrigeration is easily the largest load on a boat even when everything is done right.

40 50 amp hrs a day is not far from reality unless very well insulated and in cooler climates.

Ice is extremely cheap BTW as my students found out. We actually looked at the cost equivalency of using a Diesel powered battery charger "Ships engine running alternator" to replicate the cold froma a 5 lb block of ice.

IIRC it worked outt tot about $25.00 of charging to replicate a $2.50 5 lb block of ice.

Wingws book explores the cost of various recharging battery methods per Killowatt hour and Calders book has a lot of info on building a good icebox.

Calder advocates 6 inches of insulation, with no more volume than absolutely necessary and a drain with a heat trap on the bottom if ice, and a lid on top with two flanges with gasketing on both flanges that seal well.

Ship board AC is limited to use at dock with shore power or with on board Genset. $5-7 K for equipment alone for that genset...

If being a liveaboard with DC fridge you will easily be looking at 100 amp hour daily budget. In fact you may need to work to keep it down to that.

Once you determine your daily amp hour budget your battery nbank should be roughly 4 times larger than that. And a high output alternator of at least the same as daily amp hour demands and preferably 50% larger.

That is one expensive alternator too.

Going with dedicated starting battery off of original alternator is excellent plan with high output alternator feeding only house bank.

The course at Wooden Boat School would be an excellent primer for you if you can afford tuition and time... Somewhere around 45 hours of instruction time dealing with DC electrical systems, AC electrical systems Galvanic corrosion systems and Lightning protection systems..

[Howard]

Ray:

Do you have the ISBN numbers for Wing's and Calder's books? Or a link to Amazon, Paracay or some other source? I have one book by Wing and enjoy his work.

[Ray Frechette Jr]

If your budget can only afford one boat electrical book, this is the ONE.

http://www.amazon.com/Boatowners-Illustrated-Electrical-Handbook-Charlie/dp/0071446443

Nigel's book is also very worth having if you are going to be fiddling with big boats with lots of ssytems. You will most certainly get your money's worth out of it.

http://www.amazon.com/Boatowners-Mechanical-Electrical-Manual-Essential/dp/0071432388

[Scott Dunsworth]

Thank you Ray for your time.

Our boat will be lived on 4 to 6 months a year in the winter of south Florida.

As per the recommendation by Graham I will get my wife off the boat for a few days a week. We can do any extra battery charging at the dock along with pump outs, fueling, shopping, top off the water tank, laundry and all the other things that need to be done.

As for the marine ac, it's at the dock where it always seems hotter than at anchor that we will use it.

Graham and I have talked about foam coring the decks and cabin, which is pretty straight forward. But insulating the hull to make it more comfortable seems to be much more complicated. It is something that I will do at least in the v berth area to help keep everything drier. It shouldn't take much to knock out the condensation on the hull sides. This is an area that I am kind of a loss to figure out. It can't be to thick or I lose space on the interior. Just one more of those things I must work out before I get to far along.

Scott

[Ray Frechette Jr]

Solar panels make for very expensive power when not in a liveaboard at anchor scenario.

IE: you are looking to be actively using those panels for 4-6 months per year.

During those months are you figuring on 4-5 days a week at anchor?

If so those panels are working for you about 1/3 of the time...

From a strict dollars and cents viewpoint they may not be worth it.

However forma "Not having to listen to that diesel engine tonight standpoint... It may very much be worth it.

So, Are you planning ona a descent sized inverter too?

I plan on fitting an inverter and a Microwave to my Belhaven when I build it. I can well imagine the incredulous stares that computer screens are getting as people read this.

However to me it is worth it.

Fact is while a Micra invokes a hefty draw the duty cycle is incredibly short.

As such the 6-700 watt micro with a total duty cycle of maybe 10 minutes per day will impose a roughly 10 amp hour per day draw on the battery.

Not bad at all in my book for the convenience of the Micro to reheat our leftovers we bring from home and minimizes our actual cooking underway.

And yes I do plan to buy a solar panel to recover that draw. But then again I will only have an outboard as a kicker, and not a big diesel propulsion unit. Hence the cost justification for a descent solar panel gets easier for me. And my solar panel will not be exposed to weather 24 7 so it's life should be much longer.

I figure my battery budget is going to be pretty low on my Bellhaven. Certainly well under 40 amp hours a day.

My whole electrical system will be pretty low key too other than the inverter and solar cell.

No shore power hookup for me. o Battery charger, just the solar panel and the feed from the outboard. If it ain't gonna be sunny, I will haul the thing home and do some work and wait for a sunny day to go boating.

[Howard]

Scott:

Is this cruiser motor, sail or motor sailor?

In addition to insulation, ventilation is a key to reduce condensation. Something you learn camping in tents. A person perspires / expires a quart of so of water each night. If you don't open the tent to let air in / water vapor out, it can almost rain down on you and everything will be wet in the morning. Hard to convince folks to open doors and windows and let air in when it's freezing outside. Same with boats. Don't shut yourself up inside or you will be soaked in the morning....which is made even more difficult by the normally damp, humid environment boats operate in.

Same with heat. A dab of heat helps a bunch to dry things out, so long as any fumes or vapors the heat source omits is vented to the outside. Otherwise, the water vapor given off by the burning fuel just adds to the condensation problem.

[Scott Dunsworth]

Howard it is a cruising catketch. As of right now she will carry about 600 feet of sail on wishbones, excluding a stay-sail. She will have a 20 horse diesel to motor with. The transom is walkout with a swim platform and a door for rougher water. Sort of a modified sugar scoop. She will be 28 feet with nearly a 10 foot beam. A fixed keel and a 4 foot draft. 6'1" headroom throughout the cabin. She will have a soft dodger and Bimini. Displacement is in the 8000 pound area. The cockpit is small for a 28 with no bridge deck, the same size as my Belhaven with a long roomy cabin.

This boat is being designed from the ground up with comfort and safety as number 1 and performance and cost number 2.

I know ventilation plays a part, but from my experience with my Belhaven in south Florida (85 degrees in the day and 60 at night) in the winter it's a small part. We tried sleeping with the cabin closed up and it would rain in there. Next we tried opening all 5 ports and the hatch above the v berth, although not as bad it still wasn't good. My guess is that insulation is 80% plus of the cure and ventilation 20%.

I am trying to make this boat as dry and comfortable as possible for a 28.

We will have to run around 2000 miles of rivers every year to get to and from our winter cruising grounds, that's the reason for a over sized diesel. Because the currants in the spring going north on the Tenn-Tom will have to be dealt with.

Scott