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Hello All,

I know this may horrify some of you but I'm thinking of building a bridgedeck and cabin with 6 ft headheight on to  uncompleted 9m wharram hulls. I realise this will affect windward ability but intended use is as a coastal cruiser  and will fit big outboard. Has anybody else done this and what do you think ? Also what would one pay for two old hulls poss 6 to 8 years old (no rigging). 



ps the cabin roof would be attached to the extreme port and starboard sides of the existing

hulls and rise up to 6 feet in the middle - a sort of half circle shape at the stern end and sloping down to a front beam at the bow end.

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Innes Hutton said: What would expect to pay for a couple of old 9m hulls (water free)

Andy Best-Dunkley said:

Hi - think VERY carefully before going any further!! First, if you are thinking of buying uncompleted hulls, you should be very careful to check their condition. If they have been standing outside they may have fresh water inside = potential rot. If you buy an old, completed boat, at least you know it works as a whole to some extent! Secondly, to your question, 6ft headroom on the bridge deck on 9m hulls? This means you either will have a caravan sitting on the deck level, or the bottom of the bridgedeck will be only just above water level - neither of these are a good idea IMO! If you really want this type of cat, look for another designer's boat. As mentioned by others above, some Wharrams have been successfully built or converted to having bridge decks, but even these are much lower profile than what you are talking about. If you are considering this type of project, you might save yourself a lot of trouble to build from scratch - Shuttleworth has some designs this size, but they may not be suitable for home-builders.

Good luck anyway!

Hi Andy,

Good point the hulls I looked at are old but seem reasonably well built and rot free. Its going to be a sort of squashed bubble shape on deck . I'm also thinking of building an A-frame rig using fibre glass flagpoles for the masts. I have already chosen another design to build at a later date - this wharram is a kinda fun project. If it does'nt work I can butcher  it back as per purist plan.

Innes Hutton said:

If we all worried about reselling stuff why would we buy it in the first place. 

Raf said:

1.8 meter height cabin the the full length and width of  the hulls? It will not longer be a sailing catamaran. Will look like a humpy and the reselling value will be next to nothing. Might as well build a raft with 44 gallon drums and build a hat on it. Cheaper and will perform just the same way.

Hey Raf some people have travelled a long way on an old raft don't knock it.

Nice boats Wolf , if I was a dwarf they would be fine, I'm a professional builder.. well carpenter anyway so I should be able to do this.

I'm thinking of two 15HP engines so if I had to motersail my squashed bubble to windward I'd have 

enough power

ps no offence to any dwarfs reading this.

Wolf said:


this has been done before (i.e. by Steve Turner, a professional builder in the UK). The attached pictures show a Tanenui monocoque: no flexible beamconnections, no longer transportable, 9m long, 6ft headroom in the hulls, a nice double berth and sitting headroom in the central cabin. Certainly not a Wharram anymore, but the owner reports good sailing ability. I think this is the most you could probably do with 9m hulls. But be aware, that example was built by a very experienced professional, who kept a close eye on weight...

How big is the outboard you want to mount? For some (me) 10-15hp would be already big.



Can anyone think of a 9meter cat with standing headroom in the saloon?

Charlie said:

a lot of people have done this. it is a good idea. bridgedeck cats are very nice boats indeed! i would try and keep the weight down and keep it more aft the better.

Thanks Charlie will do.

Well Innes,

take the pictures from above and imagine the salon 6ft high, instead of 4ft (you could make a sketch). Add 2 15hp engines to that and see where the waterline will be. I'm not sure, you'll be happy with the sailing abilities. As already mentioned above: get either a motor-cat or look at other designs (e.g. fuller hulls and no V-hull).



You think you are going to get out cheap getting into a project like this.....  Then all the little bills start adding up in your build, and you find out you spent twice what you thought you were going to.  You inhaled all this epoxy dust, and built this monstrosity that has absolutely no value when you get done slamming the bridgedeck up and down the coast, and then want to unload it.  You'll be lucky if you can even donate it.  Most of these modified Wharrams look like hell, and sail even worse.  If you want a house boat, then go and buy a house boat.


With boats like" Touch Wood",  for sale, I just can't see building a wharram  right now, unless you really enjoy the process of building a boat.  Just try to build something that has some inherent value when you are done.


And if you really need to stand up with "headroom" just pick a hull to go down into, or go outside.  Plenty of headroom in the cockpit.

If u look thru my photo's there are a couple of pics with wharrams with bridge deck.

I am also buildin a Teheni with a bridge deck, the hulls were given to us, the owner said "IF U CAN LIFT THEM U CAN HAVE THEM" I was there on the weekend with two big trucks & a crane. All the best with the build / modification. YES a lot of people are horrified when u say that, but each to his own.

The pics of the ORO in my photo's has two massive inboards & the boat weighs in @ 18.5 tons. So do what you want to or need to.


I have no "philosophical" objection to you using Wharram hulls in this way. I also never consider re-sale as a factor when I build for myself.

So much for the good news.

Not many production cats at this size carry the headroom / accommodation you have in mind. Those that come close use very different shaped hulls.

I also think you are overestimating how much of a head start these hulls will give you. Google "Time for a catamaran adventure for two" an account of the building of a Richard Woods bridgedeck catamaran of this size. Note the time sheets....136 weeks to build of which only 6 were building the hulls.

Also I worry [perhaps wrongly] about your comment "only coastal use". I am just back from a coastal cruise of 3 weeks. I went to the pub...and could not get back on my anchored boat for 2 days as a poorly forecast gale made dinghy work impossible. There were approx. 12 boats in harbour..one 40 ft spent the whole first night alternately dragging the anchor / motoring back while a 26ft cruiser took her whole mooring ashore...coastal can be the most demanding sailing of all.




i get the feeling that a Wharram Design is considered as a "bitch" to build everything out of it. i saw so many of this  "i play my own designer" wrecks around the world... they rot away in a bay and the people living on it still think they will go somewhere one day...

i consider my self as a "Wharram sailor". i changed  our tiki46 design too but sticked to the plans regarding construction and philosophy.  sometimes, when people hear that i live and sail on a wharram, you can see they eyeball turning but when they step on wakataitea, they are convinced, a shame that they thought like this and they honour our achievement with respect.

i know, they will think and talk about wharrams different in the future.

it should be like this... holding up the wharrams flag when building and sailing a wharram. doesn't matter if 20 feet or 65 feet.

Innes project is one of this "optical ponk " ideas. if he is a cabinet maker, he should have building experience AND THE IMAGINATION, that he builds a elephant, not a boat.

sorry Innes but your idea is totally crap ... anyway good luck and please do not call it a wharram when you are finished.

sorry for my language but i get exited and fed up with this bullshit.

once again, "respect the designer too..."

Hi Galway Boy,

Yes I completely agree with you coastal sailing can be the most demanding and dangerous of all. (I've yet to try coastal

nightime navigation). However one major advantage to coastal sailing is you will never be too far from rescue or land

possible harbour or safe anchorage, whereas offshore you've less options for rescue but less to hit in the way of rocks

reefs sand bars, unless unlucky enough to hit a ship or submerged steel container. As you say I can only think of a few 9metre cats with decent headroom, one being a Richard Woods Sagitta which was modified to allow for the owners 

6 foot height in the saloon I think there was a price in that clearance from deck to water level was decreased slightly. Nice boat and still sailing I believe. I own a Hurley 22 long fin keel at present which took me nearly 3 years to get back in the water(this season). Yet I helped build two 22ft coastal rowing boats used for racing which were put together (from kits)(marine ply sheets with parts semi cut)in about 6 months on and off. So I think it can take longer to do up an old boat or modify it than build something from scratch. Course you may decide to do all the lofting yourself so take longer. Using computers to cut the sheets saves a huge amount of time.

Can I ask where you boat was anchored?

Hi Iain, That Oros a big boat how big are your Tehini hulls?


Iain & Cherry Mae Cairns said:

If u look thru my photo's there are a couple of pics with wharrams with bridge deck.

I am also buildin a Teheni with a bridge deck, the hulls were given to us, the owner said "IF U CAN LIFT THEM U CAN HAVE THEM" I was there on the weekend with two big trucks & a crane. All the best with the build / modification. YES a lot of people are horrified when u say that, but each to his own.

The pics of the ORO in my photo's has two massive inboards & the boat weighs in @ 18.5 tons. So do what you want to or need to.


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