Building Logs

Tanks again

Posted by Paul

I know the tank joke is getting lame. But I am still working on tanks. I get asked a lot about what the boat will cost to finish. This is a good time to discuss an aspect of this. These tanks for example. Many people building cats would buy tanks. I have 7 of them in my boat, 2 black, 2 grey and 3 fresh water. The cost of these tanks is about $500 each (on average, some would be more than that because of the odd shapes) so 7 of them would cost me $3500. I have estimated that including potable food grade paint and skin fittings these tanks would cost me $500 tops. So I am saving $3000 on the cost of buying purpose bought tanks. There is nothing wrong with buying tanks, in fact I would like to have them but in the end I dont think there will be any difference and I have a saying about spending money on other peoples labour, time I have money I dont. Having said that, if I can save enough money in the next 6 months I fully intend to pay some people for their labour to help me finish the fairing and to paint the boat in about a year.

hutton winches

It is also a good time to mention a couple of other savings I have made recently. I was on the Easy forum and another builder had changed their mind about building a cat and had some things up for sale. I bought 5 winches, all brand new, valued at $5000 on current prices for $1800 so I have saved another $3200. And to round out my savings, a friend had a not working Muir 1000 watt anchor winch that had been on his 40 ft cat which he gave me. I had it checked out and it needed a new gearbox. The electric motor is pulling very strongly. I also bought new foot switches and solenoid and all up it cost $600. The gypsy is looking a bit worn but will last a few years, so once launched I will buy a new one and keep the old one as a spare and that windlass will be as good as new. A replacement windlass is about $2600 so another $2000 saved. So that’s about $8000 saved in these 3 areas alone (tanks, windlass, winches).

I mentioned last month that I did not buy the furniture kit and that it was $15000 at the time I bought the rest of the kit and that I think I can make the furniture for about $3000 in materials using polycore ($5000 if I do end up needing 30 sheets which I highly doubt). So add that $12000 saving to this $8000 and I have saved $20000. So the cost to finish identical boats can vary by a lot of money depending on the bargains you can find or the methods or materials employed. Even the amount of outside help you get to finish the boat can change the cost greatly, do everything yourself and your build could be half the cost of someone else’s. And everyone fits their boats out with different levels of equipment so that might help explain why designers are always a bit coy about the cost of building a particular design.

Our budget (not including rent) is still $220,000 give or take 10% so anything from $200000 to $250000. For example I would like a deep battery bank (600 amp hours a 200aH battery is about $800), an large inverter, an electric watermaker, a radar and these alone could cost $25,000. I may not have the money for many of these items at launch but there will be the ability to add these as I go. I have spent just over $100000 when I include the $6000 I spent on carbon for the masts. You might be wondering why it will cost another $120,000 to finish. Go check out what they charge for a stove and oven for example. We will be lucky to get change from $2000. And a good fridge 100 litre on a boat would buy you a top of the range, double door ice making monster for a home. Our masts will come to $40,000! (we have already spent $6000 for the carbon) It soon all adds up. That is why these boats sell for half a million dollars and up and you wont get much change from a million dollars if buying an equivalent production boat.

Anyway, back to what I am doing now. For the starboard hull, I made a small ply grey water tank and it weighed more than the larger black tank so both the port side tanks are polycore and last week I glassed up more panels in order to make them. I had already measured up but I often make cardboard templates when I am making things that have to fit into tight places. I made a template of the space between the dagger case and the hull side. The template showed that the size tapered from front to back and from top to bottom by about 20mm and in order to have that tank fit. Using the templates I cut the parts for the dagger case grey water tank and then screwed it together to make a dry run of it and see if it fit. It did! I then started cutting the parts for the black water tank. This tank will sit on the chamfer panel (about a meter above water level) in a space created by the cockpit seating underside. I originally had it come to a sharp point from the bottom of the chamfer and then plumb up the front but decided to chop the bottom of the point off and have a flat base so as to better fit the exit point and not have any waste stay in the tank when it is open.

Once I had the parts cut for the black tank I screwed it together for its dry fit. Again it fit but I noticed something that might have been a problem. It wont fit through the bulkhead door. Fortunately I dont have the sides on yet so it does fit into the room through the space that will be the side deck. So once in, it wont be coming out once the boat is closed up. This is not unusual (that it will be glassed in and wont come out) but would have been a bit of a problem if I was fitting this tank after the boat was closed up.

Once satisfied that they fit it was time to glue and glass them together. A simple task, I took them apart and put them back together again only this time with glue between each join. Then once both were glued (with screws holding them together) I coved them both and wet out tapes and attached them wet on wet. And left them overnight to set.

port grey tank tapedport poo tank taped

The shape of the dagger case tank is very narrow and very tall. On the starboard tanks I have have made them with the tops left off for taping inside and the top will be glued on and will only be glassed from the outside for obvious reasons. To protect the tops of the tanks I will have the breather come out of the side of the tank just below the top and these will double as overflow points, that way the top of the tank will only get splashed but not immersed. The port black tank is also made with the top off but I wont have an overflow on this tank. On the dagger case tank I realised I would not be able to reach the bottom of the tank for internal taping if I made it in the usual way, bottom and sides, so I made it with the back off and I will make the back up in smaller sections and be able to tape them inside and out by reaching in coving the sides and running a tape over the joins as I go up the tank. About 300mm at a time will be the limit. The will mean only the top panel to close the tank up wont get taped on the inside.

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