Building 23' catamaran. Build updates

[stevemid]

I've been playing with a power distribution wiring diagram for this boat. I realise this is a bit more basic than most setups that I see here for this size boat. As always, I appreciate any and all comments/ suggestions for improvements. My objectives /comments re this design:
1. Simplicity: it is not complicated or expensive to implement and maintain. Turn two switches on when boarding, two off when leaving. One Emergency switch to join batteries temporarily for starting
2. Reliability: one battery / alternator dedicated to starting motors and has no other way of being discharged
3. One battery per motor/alternator, avoiding the problems with 2 alternators charging the same battery/battery bank.
4. Redundancy. Either battery can start either motor
5. Solar Panel planned is monocrystlaline flex panels 3mm thick, glued to the roof.

Risks or negatives:
1. Batteries can be switched off with motors running, damaging alternators.
2. No automatic limit on excessively depleting house battery (could be fixed by supplying switch panel from solar controller.)
Comments?
Electrical2.jpg

Steve

[Chimo]

Alternatively one battery per motor and one house battery charged off one motor and a second house battery charged off the second motor. Still retain the ability of connecting the motor batteries and also have the ability to connect the house batteries also if ever required. An Auto Battery Coupler set up for each motor battery and its house battery. This Steve is how I have my boat set up but I only use one ABC to charge one house battery and sometimes two house batteries if I carry the second one and connect it to the first house battery. Have had to join the motor batteries one when one motor battery failed so started that motor with the connected good battery and when the "crook" motor side was going uncoupled and started the other one as normal. Works a treat. Adding one or two solar panels to charge each house battery should be fine too as the ABC worries about the motor batteries rather than the house.

I dont think you should glue solar panels to the roof. They need air space below them.

Cheers
Chimo

[stevemid]

Hi Chimo,
Yes, I've heard that some of the panels don't perform so well when they get hot, thus the offset. However, the mono ones are made flexible to conform to the surface they are on. They have no frame etc. For looks, I don't really like the idea of a 40mm frame on spacers sticking up from the roof; rather have it hidden and take what juice I can get.

I've done a basic inventory of my planned power consumption. With a light boat is you have work to keep it light. At least on the first go, I'm going to limit myself to two batteries. The 'house' battery I have spec'd is a 150AH Full River AGM or equivalent.

[stevemid]

Moving to the cockpit, the things that needed to be built were the seating and corner cabinets; these also cover the access to the fuel tank connections. An inner wall around the sides of the cockpit had to be built. This met up with and formed a "doubler" with the vertical piece above the gunnel which extended back from the cabin sides. The gunnels extended back from the front deck halves and wrapped all the way around to cover the transom, touching almost every part of the boat.

After dry fitting the forward decks and the cabin fronts and sides, I started out by separating the gunnel from the fore deck. I glassed the outside of the cabin side to the gunnel, then removed both pieces and glassed the underside of this join.

I then re-installed this piece and glassed it to the inside of the hull. This was easy in the cockpit, but in the cabin, I had to cut access holes in the settee. The plans called for two layers of glass on the outside of the join, but I felt better having this glassed on to the outside and the inside.
Gunnel.jpgCockpit Gunnel.jpgSettee Back.jpg

This is the almost finished cockpit. I haven't glassed in the corner cabinet yet because I'm unsure of how to sequence attaching the fuel and water fillers which sit on the gunnel just in the front corner of the cockpit: If I install them now, they'll be in the way of fairing and painting. The cutouts for the fillers are too small for the clamps to fit through from the top so I can't install them from the top down, after fairing and painting. I'll probably have to make 2 cutouts in the inner hull adjacent to the fillers. After fairing and painting the outside, I'll attach the hoses to the fillers and breathers, then glass in the cutout, then paint the inside of the cockpit.
Port Cockpit Seat & Inner Wall.jpgStarbord seat and Inner wall.jpgInner Wall Aft.jpgBoarding Platform Access.jpg
Finishing the motor wells are the next project, but first I have to install the aft cleats so I can get at the backing block and the nuts before I close up the transom.

Happy Easter everyone!
Steve

[Stewey]

Hi Steve, instead of glassing in the access cutouts for the fittings, why not install a or some spinouts for these instead. That way it is easier to access these connections in the future, if you need. Personally i prefer to leave access available to all hidden connections.

Instead of spinouts, maybe use a hatch ring frame and use a sikaflex bead to reseal the cutout. This is a cheaper option than spinouts, although slightly more permanent. If, and when, you need access to these connections, it is just a matter of cutting sikaflex and removing cutout.

Stewey

[Lovey80]

This has been a fantastic thread and an absolute credit to you for your persistence and workmanship. Have you decided on the motors yet? If not my vote is to go as large as the weight will allow.

[stevemid]

Stewey,
That's a great comment, I don't know why I was thinking of sealing these up. Will do some kind of cover for sure.

Lovey80
Thanks. For motors, (remembering this is a 700kg hull with 1250 displacement) I'm supposed to stay around 100Kg each. However I built 25" motor wells so that limits me to Honda 50 or 60, or the Suzuki 60 or the Yamaha 70 which is heaviest at 117 dry weight. Still weighing up the options.

[Fed]

I'll visit the electrical for you Steve if you can give your proposed loadings and intended usage. (Trailer, moored, daytrips. overnighters?)

Don't think your 50A fuses will cut it with the starter motors, in fact why even have them?

Good plan, keep it simple.

[stevemid]

I'll visit the electrical for you Steve if you can give your proposed loadings and intended usage. (Trailer, moored, daytrips. overnighters?)

Don't think your 50A fuses will cut it with the starter motors, in fact why even have them?

Good plan, keep it simple.

Fed,
Well, if there's a direct short I want to A. not start a fire and B. protect the wiring. Do other people run unfused wires to the engines and to the switch panel? I didn't think that'd be kosher. I haven't got the motor rigging kits yet so I didn't know what size wires there I'd have to protect.

My loadings are minimal. I have a BD30 compressor for the fridge. A 3.0A sounder, a stereo, LED nav and house lights and other minor odds and sods that would be intermittant only. That would all come off the house battery. If I install an anchor winch, that'd come of the start battery and I'd only run that with the engine running.
Steve

[stevemid]

I had this question from Yallis on a "self draining cockpit" thread where I was suggesting that for offshore work I'd want substantial scuppers,

What are you building?
Scuppers below the waterline i imagine? With duck bills?

Yallis: I used to call my boarding platform the duckbill thus the confusion. I've edited my response to you below. Sorry.

My boarding platform is an extension of the cockpit floor which is about 450mm above design waterline. Scuppers would sit on the floor. There is a 100mm ledge between the cockpit and the boarding platform. If I were to get pooped, water would rush out the 500mm wide opening to the boarding platform (see picture from yesterday's update) and would leave 100mm of water to drain out the scuppers (which would be at floor level. 100mm of water in a 2M X2M cockpit would be 400 litres and weigh about 400Kg.

[Fed]

No one fuses engine cables Steve but by all means there should be a fuse for the switch panel.

Not that it would ever happen but if you did have 400 Litres of water in the cockpit half of it would go over the big opening due to the slope and the remaining 200 Litres would very quickly be handled by the 2x50 mm floor scuppers.

How do the floor scuppers drain, you'd think they would have just put a couple of holes in the transom, your floor is way higher than the water level.

[cormorant]

Steve the duckbill he is talking about are rubber hoses connected to scuppers. In smaller boats that were on trailers they used to manufacture a rubber hose that was flattened on the trailing edge .( looked like a ducks bill). The ducks bill used to trail in the water when the boat was planing and venturi effect would suck water out the scupper. Smallest piece of sand or grit or ageing rubber would mean these duckbills would weep or flood water back into the boat when stationary. These days what people are doing ( see a stabicraft) they are using a length of nitrile/ pvc flat fire-hose attached to the scupper at one end and the other having a eyelet through it and when required tieing the trailing edge above water level or letting it down to act as a ducksbill and suck water out. . The flat hose kinks as soon as a following wave hits it and stops a following wave pushing water back on your deck. Sewing piece of foam to the end of the hose means it floats the hose when at rest and stops the week into the deck and on the plane automatically lets water out.

an old thread with some links

http://www.ausfish.com.au/vforum/sho...scupper-s-!-!&


http://www.reelax.com.au/product_inf...67a59ee3129736

[The Woo]

Enjoyed reading your updates Steve. You're doing a superb job mate, the finish looks excellent!

[stevemid]

Thanks guys,
Fed,
By my reckoning at 2M X2M X.1 M (the height of the walk-through lip above the floor,) I'd have 400 L left in the cockpit. My plans show two 50mm conduits, level with the floor out through the inner wall then the transom. The inner wall is setback 180mm across the back, to create space for the motors when tilted (pics coming.) This also leaves space to install cockpit showers and deck wash either side of the walkway.

Cormorant,
Thanks for clearing that up.

Woo, I've been fairing as I go, but what you see in the cockpit looks better in the photo than it is in reality. I have 1st sanded the glassed joins but the fairing happens this week.

Thanks guys,
Steve

[stevemid]

Here's a couple pictures of the completed motor wells. The hole at the bottom is to access the bottom engine mounting bolts; this will be covered by a watertight inspection port. The hole at the top is to access the stern cleat bolts and hopefully I can run the engine control cables out here too.

I built the motor wells while the hull was still upside down and I've included several pictures of these being built as well. The 25mm ply sides were first glued and coved on to the transom which is 3 layers of Duflex laminated together. A hole was drilled in each side and unidirectional fibreglass was laid in to bond the side of the motor well to the transom. A layer of 400 double bias was laid over the uni on both sides of the motor well and on the inside of the transom. Then the sides were glassed on to the transom with three layers of double bias (100, 200,& 300 wide) inside and out. Finally a double plywood (50mm) back was glassed onto the sides; again with three layers of glass.
Starboard Wet Well.jpgPort Wet Well.jpgMotor Well Sides.jpghole glassed outside.jpgUni inside.jpgDoubler Side View.jpgComplete Motor Well.jpg