From operational concept to SOR

More from the client:

Excellent discussion all. I appreciate your comments and insights – they are definitely helping to bring focus to this project.

I asked the client for clarifications based on this conversation, and here are the answers:



Minimalism: Yes, I see their point. When I chose that word I was comparing us to our friends who cruise as a single couple on board their Meridian 57. We are definitely Spartan in comparison. But I should have thought also of Sheldon and Carmita who just paddled the entire way around Vancouver Island in their two-hole kayak. In comparison to them, even our sailboat is “Lucullus dine chez Lucullus.”

Maximum/Minimum speed: We think 8 knots would be a lovely cruising speed. Range: We’d love to not have to fuel during a typical summer cruise. That implies 500-750 miles of range.

Resupply interval: At least a month, preferably three months.

Styling: We hate the tall plastic modern yachts (like our friends’ Meridian - <wry smile>) and we love the long low skinny look of, say, an Elco of the 1930s.

Dinghy: Must have a rowing/sailing dinghy, carried on deck, with some sort of boom to get her in the water. On the sailboat we have carried both a Tinker Fold-a-Way and a wooden Mirror. Husband dreams of having a Laser, but this would have to be a second dinghy and thus in the “if feasible” category.

Head/Shower: Our sailboat head/shower is indeed about 2’ x 3’. The toilet and sink get wet when one showers. The head on our RV (caravan) was more like 3’ x 4’ and felt positively luxurious.

Oh, toilets: I spoke to my husband the engineer: No electric toilets! The simpler the better. On the sailboat it is hand-pump for emptying the bowl, with a separate foot pump to send seawater in to flush. The problem is that a wet flush demands a fairly big holding tank. We ran into a couple who had a gravity-dump permanently-installed toilet from an RV, and they could go weeks on a much smaller tank. He likes that idea.

Maintenance, Ease of use, etc.: You may infer a little of that from the way we modified the WC on the sailboat: Ease of maintenance, coupled with reliability, is more important than “one touch” ease of use. In another example, we used our sheet winches as anchor windlass, because they are simple and reliable. The ‘price’ was a bit of sweat. There are no motorized systems on the sailboat, but I suspect that, on a seven to ten tonne powerboat, we are not going to be able to hold to that line.

Size: yes, 30-40 x 12 is what we were envisioning, but we are not the experts. How about if we set a limit, say “40 feet or under” and you tell us what is possible in that size?

The professor’s office, by the way… On the sailboat it was two monitors on a 36-inch wide nav table, with him seated upon a folding chair in the passageway. On the motorboat it would be nice to have 48 inches of desk, but this definitely does not need to a “room,” it is something more akin to a “cupboard.”

We’re happy to help be decisive: Please tell us what decisions you need us to make.


Hope this helps, gents. I really am enjoying this conversation.

 

So, a long-range high-endurance hybrid-electric boat without an electric toilet - interesting. It's possible to do a direct drop toilet if there is only one (I would never recommend one on a cruising boat, though, but some houseboats do this. And lots of catamarans have a "direct drop" from a 10" hole in the bridge deck. ) A second toilet would need to be conventional mascerate-as-you-pump.

I guess the canbus control system is out. What about a washer-dryer combo, watermaker, central or zoned heat and air?

Food storage needs to be worked out. Ice boxes and cool boxes with a small onboard icemaker would be one option that requires about five minutes of daily chores to keep things sorted. I'd probably recommend one good holdingplate type icebox and a small U-line icemaker. The ice would be for the other food boxes to be distributed as needed. Or if you go for the big inverter system described below, you have the option to just adapt household appliances.

For prolonged voyaging, you want to keep the food storage completely isolated from engine heat. The cheap way to do this is via the general arrangement of the boat. Length helps a lot. But a vee drive might be a good idea on a 40'er. If it were 48 x 14, much less of a problem. Given the low and lean preference for styling, an aft engine location would seem to be the way to go. There isn't room for an aft master suite in a low 40'er anyway.

Electric system - You've got oodles of battery power, say 400Ah at 48V, and a high-power DC distribution system, both courtesy of the hybrid drive. A standard 50A shore power connector can be integrated into a pair of inverter-chargers that give you full AC via the batteries or engine. A typical bolt-on hybrid adapter gives you 5 kW of generation, plus another 3 kW from a 48V alternator. So underway, you can run everything and anything you could want. There are some significant savings in funny places if you splurge on the big inverter system. But exploiting them requires this to be decided fairly early in the design. Maybe not today, but you need to be thinking about it. The cost difference between just installing a battery charger - say 48V at 50A = about $2000 - $3000, vs a pair of something like this -

http://www.invertersupply.com/index.php?main_page=product_info&cPath=263_268&products_id=1205

specs

http://www.invertersupply.com/media/data/Datasheet-Quattro-3-5-kVA-120V-EN.pdf

is only about $2000. I suspect you can save much of that by exploiting household 120V appliances vs DC marine appliances. You might even save that much just in wiring.

 

I still have not seen a budget suggested. Without that, we do not know if this is even a feasible project, or just another unrealistic dream.

 

We are very please with our compsting toilet - a C-Head. Would never now go back to a conventional marine head.

I suggest you go look at the Skoota 36 powercat being built in Steveston. That is designed and being built as a live aboard PNW cruiser. Including washing machine and fully insulated hull with central heating

Richard Woods

 

What does a Korvet 14 CLR cost? Lets start with that

Willem Nieland Korvet 14 CLR

 

cmckesson, so how did the students do? I found your requirement pretty tight when I tried to sketch up a 40'er around a 57hp Yanmar and all the tanks needed for your requested endurance.

 

Phil: I haven't collected the results yet. Thanks for your inquiry - I will try to remember to update the forum once I have something to report.

 

HI, can any one suggest me some notes on simpson's rules , thanks

 

You should start a thread asking that question instead of taking over somebody else's thread. It is basic courtesy.