Help With House Boat Design

You have a problem with a few of the ideas/requirements.

I have been on a LOT of houseboats; usually two man sizes under 40'.

The commercial operators do not want you out above 15 knot winds or 2 foot seas. Of course, this is not in perfect alignment with the Beaufort scale and is more like a 3.5 than a 5. The issue is windage. These boats have massive high sides and can really get tippy abeam. And so, you don't want to be in 4' seas because you lose the ability to run abeam about there.

There are a few vee hulled houseboats that can perform well in bigger seas, but they are not beach friendly and much more difficult ashore.

I recommend you modify the requirements or the vessel to reflect these realities. Then, find a suitable hull form, and then take the design and modify the interior layout within reason to fit.

Making a decision between beachable and more seaworthy and even trailerable is also a thing.

So, hone the requirements first.

 

I'm starting to realise I actually want a quite mobile/seaworthy boat that you can live on rather than a barge/stationary immobile sleds that have been linked

How do you measure a hulls performance? I'm an engineer so I like quantifying these things if I can.

 

Have a look at the links for the boats for sale in New Zealand in post #8 - these are all mobile and seaworthy, and should be capable of 'doing the job'.

Re 'how do you measure a hull's performance', in what context are you looking to measure it?
In terms of speed, or seaworthiness, or comfort, or cruising range laden with stores, or....... ??
There is no 'ideal' boat - every boat is a compromise.

Do you have a rough idea as to what budget is available for building this boat?
Be aware it will probably be much easier and cheaper to simply buy an existing boat.
Ask @fallguy how many years, and how many $$'s it has cost him to build his 30' power cat. He bought the plans from Richard Woods, but the cost of the plans was a tiny fraction of the total cost of the project.

 

Hi Bajan,

Definitely sea worthiness, Safety is my main concern when I think about moving the boat. It would be good to get an idea of some criteria that effect this so I know what hulls would be suitable. I've gone away and traced out some hull plans/living layouts and seems a minimum internal area of 6m x 2.5m would be good. Anything bigger is a boon. In terms of budget, its high, I don't have a specific number as I'm in the planning phase of this project, but in the realm of $500k wouldn't be a scary number. Ideally this would be a long term project that I plan out very well before pulling the trigger. In terms of buying an existing boat, I'd be missing out an all the fun of the planning and building which is what interests me so much!

I've had a look through those boats in post #8 and there's definitely a few in there that I like the look of. Knowing a rough layout and hull type, how do I go about validating things like the sea worthiness or if windage will be a problem? Or acceptable laden weight etc. For example the boat link I posted earlier seemed totally acceptable for what I'm after, how do I know thats the hull I should continue planning with? Cheers again for all the advice its much appreciated.

 

Well, one way to define boats is real simple. Is this an inshore or offshore vessel...

Houseboats are, generally, not considered to be offshore vessels.

Of course, this leads us to the question, what is inshore and what is offshore..

Probably someone here can define it better than me, but for me, waves above 4 feet is a cutoff. I have been in some 5-6 foot seastates in a small skiff and the sea decides which way you run; not the vessel. Running abeam becomes a bit terrifying depending upon the period and even turning around leaves you wishing you were not in that place at that moment. And, I would rather be in a small skiff in 5-6 foot seas and never a houseboat. In a houseboat in rougher weather; you lose the ability to beach on the windblown sides, and you can be driven up onto the beach in even a smaller seastate. And running abeam in something like a 6' sea will have passengers praying while things are falling about. My friend did once. They made it to port, but my friend said it was quite bad and the kids were crying.

Your opening post says lakes or rivers if I read past your typo. But large lakes can be also very rough at times.

A big part of wanting a houseboat is beachability. If you want to be able to beach, a houseboat is fine for the right waters, respecting conditions. Beaufort 5, no. A 12-14' wide vessel with high sides and a barge bottom is not made for waves 6-10; not ever.

Of course, there are variations of hull forms within houseboat designs which is what I pointed out earlier. Most of the boats I have been on were super large pontoon hulls with vees forward. Their high sides and upper decks make them rather difficult to operate in much of any wind above 15 knots.

The designer of the GT27 linked above has stated that he, as a seasoned operator would be willing to take one the 80 miles across open ocean from Miami to the nearest Bahama port in the right conditions, but at the same time, says that noone ought to do it. The reason he says this is he has thousands of sea hours and understands the boat cannot get sideways. So you don't get to run the boat at will, and the sea will dictate speed and direction, to some degree, for a good pun...

The main difference between a houseboat and any other boat, for me is beachability. If you want to beach, then a houseboat with the proper hull design is the way to go, unless you want to be offshore capable which means you need a beachable catamaran.

These distinctions are all part of defining requirements. Remember, too, no boat is necessarily ideal and all of them trade ome thing for another.

The Europeans have a scale of vessel category which you ought to learn that is more practical than saying you want a boat capable of 6-10' seas. It uses the Beaufort scale, but quite honestly, I find the system a bit lacking between D and C, just as a personal opinion.

 

Awhile back, someone showed us a Category B houseboat. However, some of the marketing details said it was a Category C and I contacted the manufacturer and was told the vessel was Category C.

I have never seen a Category B houseboat. I would consider my catamaran to be a Category B.

 

When you are spending that sort of money to build a boat, you want the design to be the best possible compromise (every boat is a compromise really) that will fit the detailed SOR that you will have drawn up.
And you can be guaranteed that there are many boat plans out there, from very reputable designers, for boats that have been built, and extensively sea trialled, and proven to work.
And a lot of these boats will match quite a lot of what your SOR states.
It would be well worthwhile buying a set of plans for a boat that you like, even if it is only for the hull lines and the structural design, and then you can modify the accommodation layout to suit your particular requirements. You are not going to learn efficient structural design and hull shape design from reading a few books.

Re the Glen-L houseboat link that you posted earlier, and for which I later posted a photo, DC has already expressed concern re the size of the forward cockpit, and how it would need large and effective freeing ports to drain the water fast if a wave arrives uninvited over the bow.
Do you absolutely need a bow cockpit like this?
And Fallguy has nailed it above, noting that you do not usually associate houseboats as being 'offshore' vessels.

Fallguy also makes a very good point above re the GT 27, and taking it from Florida to the Bahamas.
It is about the same length as Richard Woods' 28' Skoota power cat which he took across to the Bahamas from Florida on various occasions I think, confident in the knowledge that she could cope with the conditions likely to be encountered - but equally nobody in their right mind would want to try to cross when the wind is blowing against the Gulfstream (which flows north quite fast between Florida and the islands), as that will create very confused waves (and this is an understatement).
At the same time one could say that Richard's Skoota is a comfortable 'house boat' in the sense that she has an efficient and very ergonomic layout, allowing Richard and his wife to live on board for months at a time very comfortably.

 

Ok I'm getting closer to what I'm looking for. I like the idea of the vessel being beachable. Doesn't need to be "Class C" worthy. I like the look of the G27 but would like something a touch bigger. Which brings me back to the Jubilee, with I guess some Large freeing ports . How do I assess if this can be beached?