Convertible catamaran widebeam

[BoatFortress]

can you take two 6ft width narrowboats and convert them into a 12ft width convertible catamaran?

Just thinking some kind of removable series of structural joins length wise down the hull, and a control mechanism for keeping both engines at halfspeed - maybe a removable prow?

Edited December 11, 2022 by BoatFortress

[Alan de Enfield]

40 minutes ago, BoatFortress said:

can you take two 6ft width narrowboats and convert them into a 12ft width convertible catamaran?

Just thinking some kind of removable series of structural joins length wise down the hull, and a control mechanism for keeping both engines at halfspeed - maybe a removable prow?

 

Yes - has been done several times - if you do a forum search you will find some of the previous threads.

 

I thik on one, the interconnect was heavy angle-iron.

 

You only need one engine - I have 'towed' broken down boats lashed alongside on more than one occasion.

 

Edit to add - if they are easily seperatable than you may need to licence boat 'halves' as independant boats

Edited December 11, 2022 by Alan de Enfield

[BoatFortress]

3 minutes ago, Alan de Enfield said:

 

Yes - has been done several times - if you do a forum search you will find some of the previous threads.

 

 

Great, could you please tell me the search terms? "catamaran" and "widebeam" didn't help that much.

Assuming seperate licenses, is there anything else required by the CRT?

[Alan de Enfield]

Just now, BoatFortress said:

 

Great, could you please tell me the search terms? "catamaran" and "widebeam" didn't help that much.

Assuming seperate licenses, is there anything else required by the CRT?

 

I agree the forum search-engine is a 'little' cumbersome.

 

To licence 'each half' will require a BSS and insurance for each-half

 

http://i24.photobucket.com/albums/c22/adfincher/Canal%20World%20Images/BoatAndrina1.jpg

 

http://i24.photobucket.com/albums/c22/adfincher/Canal%20World%20Images/BoatAndrina2.jpg

 

The two boats are owned by Gerry, a lovely old guy who lives aboard. Originally he owned one boat,found space a bit tight, and had another identical boat built. He now lives on one and uses the other as a workshop/store. The two hulls are actually bolted together using heavyweight girders, so can be separated for drydocking, but are not too easy to get back together due to ballasting issues. Both boats have engines, but Gerry normally only uses one, and steers from that boat. Gerry is very security conscious and every conceivable opening is well covered. When I first met Gerry, moored on the River Lea, painted in Battleship grey, and with his extendable, double, TV mast erected, the boats looked like a Goverment listening station!

[Rebotco]

If you link them facing in opposite directions, reversing would be a doddle!  No more winding holes needed.

Ahh deep joy  

Only thing is, narrowboats are almost 7 ft wide, so minimum beam would be more like 14 ft, rather than 12 ft.

[BoatFortress]

Great, thanks both!

 

What restrictions are there on widening the sidedoors on the shell for a better connection?

 

For example I’m assuming you can’t increase depth of the door and without risking sinking like the HMS Captain or the swedish Vasa.

[David Mack]

Just now, BoatFortress said:

What restrictions are there on widening the sidedoors on the shell for a better connection?

The individual doors have to be no wider than the space between the two cabin sides, or you won't be able to open and close them.

[Tony Brooks]

1 minute ago, BoatFortress said:

Great, thanks both!

 

What restrictions are there on widening the sidedoors on the shell for a better connection?

 

For example I’m assuming you can’t increase depth of the door and without risking sinking like the HMS Captain or the swedish Vasa.

 

Side doors are normally in the cabin side, not the hull side so no restrictions. If you are thinking of cutting through the hull side then that is another thing entirely.

[Dav and Pen]

Sounds like a butty and motor only more complicated 

[BoatFortress]

21 minutes ago, David Mack said:

The individual doors have to be no wider than the space between the two cabin sides, or you won't be able to open and close them.

 

Are sliding doors or wing doors practicable or too hard to seal effectively if closed?

 

19 minutes ago, Tony Brooks said:

 

Side doors are normally in the cabin side, not the hull side so no restrictions. If you are thinking of cutting through the hull side then that is another thing entirely.

 

so as long as connections are made only through the cabin side (assuming this means the superstructure above the hull), there will be no problems.

 

Below, and you might have trouble with wind and waves.

 

6 minutes ago, Dav and Pen said:

Sounds like a butty and motor only more complicated 

yes! Not sure if you can increase cabin level floor space when not moving though.

 

EDIT: not sure if you could resolve ballast by pumping water between the tanks.

 

Edited December 11, 2022 by BoatFortress

[TheBiscuits]

Also think about where you're intending to use them.  

 

I do quite a lot of locking with a breasted pair on the Northern broad canals, and it's quite annoying how often I need to separate the pair to get through lock gates that don't quite open far enough.

 

It's simple enough to release lines - if sometimes a bit fiddly in the bottom of an empty lock - but would be much harder with a bolted structure and impossible with a welded structure.

 

You don't really want to be stuck in a lock waiting for staff to come and fix the gates overnight if it's not something you can sort yourself.  At the very least carry a long handled keb and a grappling hook as well as the usual poles and boathook.

[Steilsteven]

I've often mentally toyed with is idea in the past but realised that there is no great advantage to be had.

It amounts to creating a vessel with the disadvantages of both a narrow boat and a wide beam.

 

Keith

[BoatFortress]

 

15 minutes ago, Steilsteven said:

I've often mentally toyed with is idea in the past but realised that there is no great advantage to be had.

It amounts to creating a vessel with the disadvantages of both a narrow boat and a wide beam.

 

Keith

True, initial cost could be a factor if widebeams are significantly more than double the cost of narrow, you want to travel on more canals, or want to be able to effectively up or downgrade floorspace.

[ditchcrawler]

Some of the hotel boats seem to manage OK breasting up at night with a canvas covered hatches between craft.

 

Edited December 11, 2022 by ditchcrawler

[Alan de Enfield]

1 minute ago, BoatFortress said:

True, initial cost could be a factor if widebeams are significantly more than double the cost of narrow,

 

But they are not.

Certainly a 'newish' widebeam will cost considerably more than 2x 40+ year old NBs but you are not comparing like for like.

You do not need to pay for two-engines, two bathrooms, etc etc etc with a widebeam, you do not need two BSS certificates, two licences or two insurance policies (depending on the permanence of the 'connection').

[blackrose]

3 hours ago, BoatFortress said:

Just thinking some kind of removable series of structural joins length wise down the hull, and a control mechanism for keeping both engines at halfspeed - maybe a removable prow?

 

Removable series of joins... You mean ropes? What would be the point in anything more structural?

 

Unless it's a temporary arrangement the other problem is that once you start to get corrosion between the two hulls you won't be able to do anything about it. 

 

To be honest since this "catamaran" is never going to give you more space than two narrowboats I'm struggling to see what the advantage is over two narrowboats which you can either move separately or move together, either with one towing the other or breasted up side by side.

[BoatFortress]

1 hour ago, blackrose said:

 

Removable series of joins... You mean ropes? What would be the point in anything more structural?

 

Unless it's a temporary arrangement the other problem is that once you start to get corrosion between the two hulls you won't be able to do anything about it. 

 

To be honest since this "catamaran" is never going to give you more space than two narrowboats I'm struggling to see what the advantage is over two narrowboats which you can either move separately or move together, either with one towing the other or breasted up side by side.

 

Yes I meant either ropes, or some kind of reconfigurable joint bracing system to keep doorways in line.

 

1 hour ago, Alan de Enfield said:

 

But they are not.

Certainly a 'newish' widebeam will cost considerably more than 2x 40+ year old NBs but you are not comparing like for like.

You do not need to pay for two-engines, two bathrooms, etc etc etc with a widebeam, you do not need two BSS certificates, two licences or two insurance policies (depending on the permanence of the 'connection').

Yes, I guess the costs of two BSSs, licences, and insurance policies would add up, even if you take out the initial cost of the boat(s) and don’t compare like for like.

[blackrose]

If you beast up two boats and manage to line up the hatches you've still got to get out of one boat and into the other.

 

Even if you cover the hatches into a passageway between the two it's not going to be like having the space of a widebeam because you'll always be sitting in a narrowboat sized space whichever vessel you're in. 

 

My advice would be, if you want a widebeam buy a widebeam, if you like narrowboats but need more space and you can afford two then buy two narrowboats. But don't buy two narrowboats and try to join them together thinking that you're somehow going to create the space of a widebeam because you won't - at least not without creating a lot of other problems.

Edited December 11, 2022 by blackrose

[BoatFortress]

2 minutes ago, blackrose said:

If you beast up two boats and manage to line up the hatches you've still got to get out of one boat and into the other.

 

Even if you cover the hatches into a passageway between the two it's not going to be like having the space of a widebeam because you'll always be sitting in a narrowboat sized space whichever vessel you're in. 

 

My advice would be, if you want a widebeam buy a widebeam, if you like narrowboats but need more space and you can afford two then buy two narrowboats. But don't buy two narrowboats and try to join them together thinking that you're somehow going to create the space of a widebeam because you won't.

indeed I guess I could make a secondary “floor” at the height of the hull but that would mean extending the roof/awning by that much in that area of the boats which would need a lot more cutting into the shell, with attendant waterproofing and insulation issues, and would need to take down that bit for low bridges or seperation.

 

Unless I just have a covered large area at the front or stern rather than in the cabin middle.

[Ianws]

Would a permanent floor be a problem as the trim of the 2 separate boats would fluctuate with the amount of  much water was in the respective tanks?

[ditchcrawler]

14 minutes ago, BoatFortress said:

indeed I guess I could make a secondary “floor” at the height of the hull but that would mean extending the roof/awning by that much in that area of the boats which would need a lot more cutting into the shell, with attendant waterproofing and insulation issues, and would need to take down that bit for low bridges or seperation.

 

Unless I just have a covered large area at the front or stern rather than in the cabin middle.

Have you done any narrowboating on the canals?

 

[BoatFortress]

19 minutes ago, Ianws said:

Would a permanent floor be a problem as the trim of the 2 separate boats would fluctuate with the amount of  much water was in the respective tanks?

fair point, you’d need to rebalance it constantly, and the floor would be constantly tilting slightly.

[blackrose]

41 minutes ago, BoatFortress said:

Unless I just have a covered large area at the front or stern rather than in the cabin middle.

 

But then you're just crawling around from one boat to the other and finding yourself in another equally sized space.

 

If you want to do that then what's wrong with stepping outside onto the decks of two breasted up boats or walking along the towpath for 20 yards if the two boats are separated? I really think the idea of joining two narrowboats is nonsense with no benefits over the options I've outlined above.

[BoatFortress]

28 minutes ago, blackrose said:

 

But then you're just crawling around from one boat to the other and finding yourself in another equally sized space.

 

If you want to do that then what's wrong with stepping outside onto the decks of two breasted up boats or walking along the towpath for 20 yards if the two boats are separated? I really think the idea of joining two narrowboats is nonsense with no benefits over the options I've outlined above.

 

Yes that makes sense, it's not really practicable, at either front, middle or back.

For reference I mean something like terrible mspaint cross-section on part of the boats length - with the dashed green being an awning, orange being a part removable section and red being temporary raised flooring - but even stuff like a tilt would make it tricky.

 

 

Going to go back looking for budget widebeams I guess, although I could start with a narrowboat and sell it for a widebeam in a few years bearing in mind depreciation. 🤔

[ditchcrawler]

2 minutes ago, BoatFortress said:

 

Yes that makes sense, it's not really practicable, at either front, middle or back.

For reference I mean something like terrible mspaint cross-section on part of the boats length - with the dashed green being an awning, orange being a part removable section and red being temporary raised flooring - but even stuff like a tilt would make it tricky.

 

 

Going to go back looking for budget widebeams I guess, although I could start with a narrowboat and sell it for a widebeam in a few years bearing in mind depreciation. 🤔

That would be about 3ft high. as I said earlier do you have any experience of Narrowboats?