Building my 36' ply catamarran.

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This is the dream that has consumed my life for the last 10 yrs. I have posted a few videos of my initial voyages on u-tube. See u-tube user name; "alanrb1". Don't forget to vote if you enjoyed. Thanks! I have started talking about it in my blog

 and since this guide allows for photos I'll put a few in here. There are probably other boat tragics out there. We can provide therapy for each other and maybe even some support or encouragement.

Although I'm not quite up to that stage, I will document the choice and selection of sails in some form. I'm still feeling my way around with this "guide" and the blog. I would love to hear from anyone who is building their boat. If you're looking to save 50% and up to 90% of the cost of sails by buying second hand, then I will try and help with that. I can help with cost effect professional alterations and can almost always come up with a few options. Even if you don't buy from me but privately, I may be able to help you with hardware and information about DIY sail cutdown, alteration, adding reef points, replacing/repairing uv protection on furling genoas. I've been doing all this type of work commercially, up until recently, when the final launching goal was committed to.  

My boat started life as a Tangaroa IV cruising cat designed by James Wharram. I have changed a lot of things on the boat in my attempt to increase interior space, especially add double bunks and a lot more headroom. Another thing I did was straighten out the sheer line of the boat. A Wharram purist would say I've bastardized a  beautiful design, and all I can say is 300mm of extra headroom had to come at some price. Some of Wharrams features are good, but I need a boat that sails to windward well, so I will be adding a centerboard. For a boat of this length the design interior space is not great. 5' 8" headroom may be ok for James Wharram and his ladies but I need minimum of 6'2"

Nor do I like Wharrams rubber compression beam mounts. The bolts are always a way for the water to get into the boat, and that spells disaster on a wooden boat. I wanted a way to fix the beams in place with out all this flopping about. I have chained the beams on to the boat. Now there is minimal movement and now there is more possibility to build between the hulls. The cockpit is connected to the left hull. This allowed for a space big enough for the bar fridge to fit inside the left hull without encroaching into the walking space. I'm very happy with the way it's turned out.  Eventually I would like to glass the beams into the hulls. Its only time that's all. Will it ever happen? Not sure. Every thing is simply a matter of priorities on a boat. There is always plenty to do, boat owners will know what I mean, and there is always places to sail to.

I like to keep things simple as far as possible. After all we want to have a peaceful time on our journeys, and simplicity is a good starting point. That's why so far I have avoided roller furling. I can see why monohull sailors like it. It's dangerous on the bow of a monohull. Not a place to spend much time if you ask me. It's not so bad on a multihull. There is probably going to be less green water coming past, and a bit more level working space. 

          I'm also pleased with my bimini set up. It's a trampoline frame, the type you jump on in the backyard, light weight gal steel. I have bogged up the holes where the springs attached to keep the water out. I sprayed Penetrol in the holes to arrest any rust before closing the holes. This frame holds up my tarpaulins which are so good for converting the cockpit into cosy area for a BBQ or sit round on deck chairs for a meal or a chat. If its a bit cold we leave the BBQ going on low to create that warm environment that we like to relax in. 3 sides of the tarpaulins roll down to make a weather proof enclosure. I used the black trampoline cloth to make my rear trampoline that the dinghy sits on. Its just recycling really.

I've got a lot of  photos, but since this is my first 'guide' I wont get too carried away for now. Thanks for looking and if there is anything I can help you with please contact me any way you see fit. 


THE WIND GENERATOR  (added 11Mar09) My Wind generator has finally hemorrhaged. It did outlast the warranty, so that is good. However, I have decided not to replace it and to stop selling them. I prefer to sell things that I use myself and believe in. Wind generators have moving parts. In high winds they can be dangerous and noisy. My thinking now is that the money is better spent on solar panels. Even on cloudy days I am getting enough power to run my 240v bar fridge. On a sunny day I have to disconnect 2 out of 3 of my panels by mid morning, to keep the charge voltage below 14volts. I don't have a voltage regulator because I take the panels off the boat while not in use. I paid $1500 for 294watts, second hand, less than a replacement wind generator. What a good problem to have! too much power on a sunny day, or enough power for me to use all the power tools or my wife to use the hair dryer!  On a cloudy day when I could sometimes use a little extra power, tracking the sun is redundant anyway. The cloud diffuses the light so that tracking makes very little difference. 

THE FRIDGE is just a normal 240volt bar fridge you would find in many homes. Many of the 12volt fridges available on the market are very cute but just not big enough and they are very expensive compared to the 240volt. Some are also quite noisy. Also you may not be able to have both fridge and freezer space in the one unit. I have replaced the wire top shelf with a clear polycarbonate shelf. This means that above this shelf everything freezes, but below, it stays as a normal fridge. The really cold air around the freezer box is prevented from circulating around the lower part. So you can have more or less freezer space simply by moving the polycarbonate shelf up or down! How good is that? I wind the thermostat up to very cold without freezing my veges below the solid shelf.  My bar fridge cost $50 over 10years ago and is still going strong. I have a 4800watt inverter which cost about $150 on ebay including freight, so you can see my setup hasn't broken the bank. The other thing that's great is you can organize a fridge with shelves a lot easier. These esky type fridges can become a disaster area where your liquids are running out of their containers, and every thing is just "tipped" in on top of everything else 2 or 3 layers deep. Ok the cost is a little bit more power consumption with the bar fridge. There is 10% to 20% loss of power through the inverter. It's a price I'm prepared to pay for one of the comforts of home. I try to keep the fridge closed between meals. This procedure helps to reinforce my no grazing between meals philosophy. Then again there is always the nuts and dried fruit. (Enemy no. one!) You may have noticed on board that body weight is not really a problem. We are constantly on the move up and down steps, bracing ourselves, etc. It's a healthy life!

14.7.11 Fridge update. I have replaced my 240volt fridge with a 12v fridge and a separate 12v freezer. The added efficiency and fexiblity means that even when it is cloudy we seldom ever have to start the generator. 

PETROL GENERATORS; I have a 850watt one on board to help run my wife's hair drier. It is ex Bunnings refurbished 750watt that only cost $79 on ebay. These generators are really only there for backup now that I have enough solar panels.  I have approx 500Ahr of battery capacity a total of 6 batteries weighing about 30kg each.

 My BATTERY CHARGER is 30Amp fan cooled. I monitor the battery charge state using a simple volt meter. Maximum battery charge is 12.6 or 12.5volts, measured without load and while not charging. It never gets that high while we are living on board because the charger would have to reduce its charge rate to avoid damage to the batteries. (Maximum charge voltage 14.2volts) However after being away from the boat a few days, I get the bonus of fully charged batteries, thanks to the efforts of the 20watt solar panel. I don't have a regulator for my solar panel. When I'm away I disconnect the 294watt panels and leave only the 20watt panel connected, which is insufficient to need a regulator. So while living on board the battery voltage (no load) ranges between about 12.1 volts and 11.5 volts (at which point the inverter will switch itself off) To maximize battery life always try to maintain  as close to full charge as possible especially while not in use. Always have your battery box well ventilated and have no sparks or source of ignition near as the hydrogen and oxygen gasses released by lead-acid batteries being charged can cause a big bang! Lead-acid batteries still the best value way of storing power. Not so popular on boats that lean over a lot. Another plus for  multihulls.


The dinghy will be retrieved using muscle power.  The back trampoline slopes down towards the water allowing enough space to pull the dinghy between the trampoline beam and the main structural beam, see photo.  The main winch could be used, but in reality is not required. The winch is well positioned to tether a drogue or sea anchor. I have yet to mount one on the other side. It is true we have sacrificed the rear trampoline for dinghy storage, but ability to launch quickly is worth it. Davits are more weight, more $, more things to go wrong and slower to operate. Most times keep things simple is best.


The 2nd day afloat in the Macleay river, after launching, we had a strong westerly. With the wind gusting under the rail bridge, the boat would pick up speed going in reverse when a gust would hit, and when the chain went tight, the anchor would drag a little bit. The action is called snubbing, and the effect over a day or so is that the boat is moving slightly with each snubbing. I fixed this with 2 actions. 1.) I replaced my expensive Mawson  Plough, complete with lead, with my Bruce anchor. The Bruce was to be the backup, but its holding in mud is unrivaled in my opinion. It has also worked well in sand and is now my main anchor.   2.) I have a 25kg steel weight which I allow to run down the anchor chain  about 3m. This smooths out the snubbing action, and makes laying at anchor more comfortable. I have left my boat unattended at anchor for weeks without any movement.


The standard Tangaroa mkIV weighs 2.8 tons. My boat weighs a bit more than even the highest guesses. However the 4 main beams are solid hardwood and parts of the keel are also hardwood, and this has added maybe 200 to300 kg. Also I have built a centerboard casing into the inside of the left hull and if I need all the comforts of home then I have to cop it!  Fridge, freezer, microwave,  4 generators systems no less, a pile of batteries 5 x 20kg, big anchors, big chain, 150L water 100L fuel gas bottle, and so the list goes on. Total 5.1 tonnes and counting......

Final weight with all fuel, water, food, etc 5.3 tons as lifted into the water. I'm going to add a few feet to the main mast to help compensate. I can't have a situation arising where I'm being caught by a monohull, and I've run out of secret weapons. Sometimes I just need a good reason to get off my backside and hoist that huge mast head spinnaker, and feel the acceleration. It has taken days to get the grin off my face in the past after a good days run under spinnaker. My 1st Tangaroa spent hours wound off the clock, the speedo only went to 15knots, and it was only a standard ketch rig! 


 Now having completed a small delivery voyage from Kempsey NSW via Southwest Rocks to Sydney I am going to reveal a few observations regarding boat building. (My style) I'm feeling a little more bold now, to reveal some of my folly. Some of us love to hang onto the dream of building and sailing our boat. The trick is to bite off what you can handle and go for it. 10 years is a bloody long time to be building a boat. I wouldn't recommend it to anyone. While I have owned one of these Tangaroa catamarans before, also bought as an unfinished project, this current project had the following drawbacks (1.) To far from home 9hrs return trip up the pacific highway to Kempsey from Sydney. I owned land in Kempsey and figured it would take 3 years to complete the project. In fact the project took 10years, and I estimate I made a total of approx 70 trips! (2.) This boat was bought with rot in the keel. The decks were not sealed and rain water and over-night dew continued getting into the boat and the rotting continued for about the first 3 years of the project, making a manageable project into a huge one. Rot is always far more extensive that it appears when first discovered. With hindsight, I didn't save anything by buying an unfinished project with rot, even though the cost was only $500 for the whole boat,( almost complete but without mast.) If  I knew what I know now, it would have been different, but we learn by doing, and finding out what works and what doesn't.  (3.) In these early years I used a lot of polyester resin and fiberglass. Bad choice! Epoxy is a little bit more expensive but sticks 10x better to plywood. It even sticks to damp wood. If you build outside exposed to the elements, as I did, occasionally it is preferable to glue damp timber than to wait for perfect conditions.  Virtually all the early polyester work that I did, I have now replaced with epoxy. While I have used a little bit of liquid epoxy resin, I found the glue (gel) by Fiberglass Asia very easy to use. The components are mixed 1 to 1 so you don't need any fancy measuring device. Just 2 blobs on a mixing pallet and a large spatula (paint scraper) and a couple of mixing/spreading knives (I just used a couple of old dining knives with a bit of flex in the blade). To make filler just add sawdust. To make a waterproof non skid deck surface, apply the glue with spatula and sprinkle saw dust on top. One thickness of light woven glass is even better. The saw dust on top provides a good key for paint and no need to sand before painting. The finish is a durable non skid finish. The glue works fine with woven fiberglass too, not too thick though. Use liquid epoxy on multiple layers of glass. In cold weather preheat the glue components in a microwave to make it easier to spread over the glass. Heat first, mix second, because it will go hard much quicker while hot! Remember reaction speed doubles for every 10 degrees c. heat rise. Experiment with small quantities first, to minimize waste. To make anti fouling which will last 10 years, add copper powder  to epoxy glue and apply with spatula. I got my copper powder from Australian Metal Powders. To make any color epoxy paint add pigment used in colouring concrete available at hardware stores. All these coverings can be applied up side down, the ultimate in versatility. I repaired a crack in the black nylon lip of a winch using the black pigmented glue, and used a wire to reinforce the rim, covered with the black epoxy. It looks like new and works like new. If you want to speed the cure rate, put your work in direct sunlight, or use an old hair drier, or a heat gun to keep the glue warm. This makes working between tides possible when beached. I have had the glue going hard in half an hour using my wife's hair drier. Great for closing up leeks or holes between tides. Yet another advantage of cats!  But my monohull friends, please don't get rid your mono's. I need someone to race against that I have a chance to beat! Any 2 boats going in a similar direction, is by definition, a race! (unless your not winning, then try putting the motor on as well, if that doesn't work then change tack to get the so'n'so out of your face. Am I right?) 

     So those are some of the things that didn't work so well. It cost me in time and money to learn these lessons. If you can get someone who is a successful boat builder to give you a bit of guidance, do it! Over the years many of my customers shared things with me that proved invaluable. Thankyou all! Now its my turn to keep the good oil flowing, and pass on their knowledge.


There are many things that did work well. For example; I have just used Dulux house paint on my boat with excellent results. Super enamel on the hulls (2 coats by roller) and Weather Shield (water base) on the topsides. Marine paint is a ripoff and no better value in the long run. The Dulux Super Enamel did have to be touched up just above the waterline. I used a single pack polyurethane for that but most of the Dulux is still doing fine 5 years on.


    My wife and I will be sailing to NZ 2014. After that it's North through the Pacific Islands in a big arc and back to Australia. There is much finishing work to be done before that; add the center board, plus many smaller jobs.


Center board is now fitted and has made a huge difference. It is 3m x 0.5m x 0.1m mostly Oregon pine glassed over with 1 layer chop strand mat and 1 layer of woven glass rolled on top using epoxy. Boat speed is dramatically improved going to windward. Ability to point 45 degrees to the wind. Easy to go about when tacking. Easy to balance the tiller for self-steering. Depth warning at 1.5m depth when board down. Ability to hove to using triple reefed main and no headsail. See my u tube video to see the board and case.

Above left; Winching up the new mast. Middle; new mast and boom in place. Right; Jib and spinnaker run with the new rig. 

When I continue writing this guide I'll have more to say about that. Building and sailing your own boat anywhere around the globe is within the capacity of anyone! Its making the right choices and keeping going with that goal in your mind that will determine your success level. I will be adding to this guide as time permits. If you have found this guide helpful, please help me a little bit by voting below. Thanks for looking and keep coming back!


PS The videos of the boat under sail are at "alanrb1" on u tube.

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