Designing and building a houseboat

Thanks for this, I appreciate and understand the advice given seeking the expertise of a technician etc. but this is something I really want to do ..... understanding the process to me is as important as the end goal and have lots of time .....being self employed and semi retired....
The sea conditions you refer to.... It is a very quite lagoon with wind driven waves of no more than 100mm .... the wind can be a factor and the current is definitely a factor but generally not where the boat would be moored.

 

Wow Sam Sam now the creative juices are flowing..... going to have a good read of this and start my design again. Many Many thanks

 

I didn't say anything about technicians. I sort of wondered why you said no pontoons and then designed pontoons.
A catamaranny/pontoony hull can be harder to steer than a monohull hull shape if only one engine is used.
I had looked on google maps and saw you have pretty calm conditions and a fairly large tide. What sort of hulls do other houseboats there have?

oops crosspost

 

Apologies the technician comment was referring to an earlier post not by yourself at all but I was so appreciative of your understanding, firstly of my ignorance and secondly of me wanting to do this journey without being told to send it to a "technician"
Yes Knysna lagoon is special .... there are not many houseboats but those that are here an an eclectic mix of 45 gallon drum pontooned boats to classic flat bottomed canal boats. Half of which cannot get under the bridge so miss out on the entire experience of the lagoon. There is not enough of any one design to set a trend, many of the owners i have spoken to seem to have one way or another "inherited" the boat and would all love to have the opportunity to start from scratch.
Yes I think the Mono Hull route is the way to go. back to the drawing board......

 

I am a bit confused here, maybe it is the terminology used.... I hear the deck must always be above the waterline, what I was referring to was the actual floors of the cabins, that can surely be below the waterline therefore reducing the the centre of gravity making for a more comfortable experience in the houseboat. The sundeck on the roof will dramatically change the centre of gravity if all six people decide to go tanning.... but this needs to be no higher than 2.5 meters from water level in order to clear the low bridge therefor my negative assumption of the freeboard.

 

If you don't get enough headroom with whatever you draft ... you could make it like a popup camper. I don't know the scope of what you are planning but if you intend to keep it light then you aren't going to draft much with a flat bottom

 

@JohnMarc, Indeed, the floor is one thing and the deck is another. I refer to the deck, that is, you are right, just a matter of nomenclature.
Your boat looks very stable so do not condition, for the time being, her forms to CoG, although you should do a preliminary study, as soon as possible, of weights, their CoG and the stability of the pontoon.

I totally agree and, as I said before, in my opinion that's not good

 

Silly question maybe but does a deeper draft minimise the list or susceptibility to heel. I am looking to accommodate about 8,5 tonnes ..... so not keeping it light, my main concern is the overall height has to be less than 2,5 metres in order to get under a low bridge on the lagoon. I will probably use your suggestion of a pop up camper to create additional cabin space on sunroof.

 

Your so low that I don't think it's going to be unstable unless you go out of your way to not balance the heavy stuff. Your beam will give you stability, make it wide.

 

It is already clear that the boat is so stable that you can do almost anything you like. Let's now consider what would happen if the wind pushed on such a large lateral surface compared to the submerged lateral surface, drift surface, that it is very small.

 

True That!

Just for that reason I would think a flat bottom is probably not the way to go.

 

Okay my ignorance again.... what is exactly is the drift surface...... I did originally think I was Going pontoon as picture below but realised it probably would not clear the bridge but surely the lateral surface (I assume that would be the surface of an object exposed to wind)would surely be the same wether flat bottomed or pontoon, I assume we are talking from the side and not front or back.

 

Okay so then having gone from potions only then flat bottomed being a possible no no could a combination like I have done here possibly work, the floor level is low.... keeping the CoG as low as possible for the sundeck .....

 

You will have a hell of a time controlling it in a blow if your perched ontop of the water which is what will most likely happen with a flat bottom. The cat hulls or better a mod v would be better.

I guess I posted same time or just missed that last post viewing on my phone. That would be better but clearance between the hulls reduces headroom so probably better to go with a slight v hull flattening out in back as previously mentioned.

 

Fantastic, Okay so the slight "v" in the flat bottomed design will minimise the impact of lateral force....or"wind" in my simple english ha ha? If that is the case should I be positioning my heavy items like water tanks, batteries etc as close to centre (or in the "v") along the length of the boat creating almost a centre weigh (keel) or will that create more movement like a pendulum effect? My way of thinking is construction engineering .... this calls for a very different approach I am coming to realise. The alternative approach of course is batteries along the one edge with the counterbalancing fixed heavy items along the opposite edge, with the varying weighted items (and I am sure there is a term for these type of items) such as water tanks luggage holds etc along the centre. I really hope this last question makes sense?