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i have been given the go ahead by the other half i can build my own narrow boat in the back yard but its only going to be 20ft-25ft long as its only going to be used on weekends and the odd week a year. are there any plans online to give me some dimensions around the prop area of the boat.

also have been looking at one of these engines, item number - 321506504738 there 2 cylinder 13hp kubota engines, do you think this will be enough power with the right gearbox.

thanks

 

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13 horsepower should be plenty, the problem will be finding a gearbox (Or, to be more exact, an adaptor plate) that will fit and reduce enigne speed enough to drive a propeller with reasonable efficiency. Good luck.

 

If you get chance, you might want to have a look at and borrow the dimensions from a Springer Waterbug, or a Sea Otter.

  • Greenie 1
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I used to have 32ft NB with a 12hp single cylinder inboard and that got along very nicely.
Two reasons I wouldn't choose an outboard are the (lack of) petrol availability on the cut, and poor battery charging performance. I know there are diesel outboards, but when I looked they were very expensive. Outboards do have some advantages though, as we found on our cruisers many years ago. We did have a brand new Johnson nicked off the boat though.

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if you only plan to use it occasionally there may be a good case for having a trailerable boat which allows you to explore different parts of the system and does not require a permanent mooring which will limit your range.

 

I went through the same thought process and ended up selling my widebeam and buying a nice traditional cabin launch which can be trailered. You could build similar?

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if you only plan to use it occasionally there may be a good case for having a trailerable boat which allows you to explore different parts of the system and does not require a permanent mooring which will limit your range.

 

I went through the same thought process and ended up selling my widebeam and buying a nice traditional cabin launch which can be trailered. You could build similar?

I doubt you could build an all steel boat and keep the weight down to 3 tonnes which is pretty much the limit for a trailable boat.

 

Personally I would go down the outboard route despite the drawbacks. I think the new generation Hondas are fantastic machines and the BF20 would be more than enough for a 25 foot NB.

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thanks for all the suggestions, i want an onboard engine so i can get fuel easy and having a knackered back i wouldn't be able to carry an outboard or carry cans of fuel without feeling the pain the next day. we do plan on buying a bigger boat in a couple of years to live on once the kids have gone. but for now i need some thing to keep me busy.

i was thinking of making it 5mm bottom 4mm sides and 3mm top to keep the weight down so i can trailer it then put the ballast in later. and because i can't sell it for 5 years anyway i was thinking of just scraping it when time comes to buy a bigger one.

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thanks for all the suggestions, i want an onboard engine so i can get fuel easy and having a knackered back i wouldn't be able to carry an outboard or carry cans of fuel without feeling the pain the next day. we do plan on buying a bigger boat in a couple of years to live on once the kids have gone. but for now i need some thing to keep me busy.

i was thinking of making it 5mm bottom 4mm sides and 3mm top to keep the weight down so i can trailer it then put the ballast in later. and because i can't sell it for 5 years anyway i was thinking of just scraping it when time comes to buy a bigger one.

Surely it will be 7 years old when you come to sell it? ;)

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I would get an outboard and convert it to run on LPG, easy enough to do I would imagine. The kits for genies are about £100? Then you can just get the canisters from any Maria and try can swap em out for you- no heavy lifting. Very economic on running ans service intervals are not so frequent as its a lot cleaner.

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I would get an outboard and convert it to run on LPG, easy enough to do I would imagine. The kits for genies are about £100? Then you can just get the canisters from any Maria and try can swap em out for you- no heavy lifting. Very economic on running ans service intervals are not so frequent as its a lot cleaner.

Interesting idea.

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Many (most/all?) professionally built NBs are built by two companies. One does the steelwork, then another does the woodwork and fitting out.

DO you have both sets of skills. Remember that boats have few straight lines and fewer right angles so lots of basic building and kitchen fitting skills are challenged in the new situation. Likely a contractor does the painting and a signwriter does the lettering and diamonds.Usually a good GRP boat will be a lot less money than a steel boat.

 

A cruiser could well be within your car's towing weight if you want to change waterways in a hurry, read the car's manual first.

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i just don't like the look of an outboard motor on a boat don't no why and i like the sound of a narrow boat with a proper engine.

i can fit it out no probs and have been painting cars for about 10 years on and off helping a friend out on weekends when he has to much work on so will be able to give it a nice paint job when its done.

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Just a couple of points to consider :

 

1) An inboard engine, gearbox and shaft will take up about 6 foot

The stern will take up another 2 or 3 feet

The bow will take 5 or 6 feet.

 

That's about 12 feet of your 20 feet. Can you fit your wife and kids in an 8 foot space after you have installed beds, toilet and kitchen ?

 

2) You plan to buy a bigger one and sell/scrap the 'home-build' after 2 years - Do you think that it will be finished in 2 years ?

 

If you plan to make it "trailerable" you will be looking at a lot of expense to make a roadworthy trailer to carry 3 tons or so - buying a new trailer will be £0000's+

You will also neeed a car something like a Land Rover to tow it - A discovery has a maximum towing limit of 3500 kgs - including the trailer (which will probably weigh a tonne +) The boat trailer I had for a 2 tonne GRP boat weighed 900 kgs (it was an indespension built trailer

 

Link takes you to a boat trailer that carries 2.2 tonnes and has an empty weight of 1300kgs and costs £3811

 

http://www.indespension.co.uk/bunked-trailers/92-big-dipper-3.html#product-tabs

 

If you are looking to get a boat on a limited budget, you can pick up a very reasonable GRP boat around 30 feet for £3000-£5000, it would be usable immediately and give you time to save up for the bigger boat in a year or three

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thanks for all the suggestions, i want an onboard engine so i can get fuel easy and having a knackered back i wouldn't be able to carry an outboard or carry cans of fuel without feeling the pain the next day. we do plan on buying a bigger boat in a couple of years to live on once the kids have gone. but for now i need some thing to keep me busy.

i was thinking of making it 5mm bottom 4mm sides and 3mm top to keep the weight down so i can trailer it then put the ballast in later. and because i can't sell it for 5 years anyway i was thinking of just scraping it when time comes to buy a bigger one.

Have you done any weight calculations?

 

There's no way you can build a 25 foot boat with an inboard engine to those specs and keep the weight down to a trailable level. The boat needs to be under 3 tonnes.

 

Springer Waterbugs were just trailable, built with 3mm steel throughout but with an outboard engine.

 

You would be struggling to do it even with 20 foot, but a 20 foot boat with an inboard just wouldn't work unless you can think of a way of accommodating the engine in the cabin like the old 22/23' Freeman cruisers. You might be able to fit a Z drive perhaps.

 

As regards a "proper" engine, I'm not sure what you mean. Also bear in mind you will have to think about soundproofing in such a small boat if you ever expect to have the engine running whilst you are in the cabin. That's another reason why an o/b makes so much more sense. If your back is so bad you can't do moderate/heavy lifting how are you actually going to build this boat?

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To give you a very very rough weight estimate 7metre (23 foot boat)

 

1m x 1m x 5mm of mild steel weighs just under 40 kgs

 

Take a base plate 7m x 2m thats 14 x 40kg = 560kgs

Take 2 x sides 7m x 2m thats 28 x 40kgs = 1120kgs

Take 1 roof (allowing doors etc) 7m x 2m = 560 kgs

 

Thats roughly 2240 kgs for the bare hull - no allowance made, bracing,ballast, tankage, for the taper of the bow, or the swim at the stern

 

Add an engine, gearbox and fit out and you will be way (weigh) over the 2.5 tonnes + 1 tonne trailer for towing

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20 - 25 ft is not much for a narrowboat and, it would, I think, would be very hard to make it look attractive, it is very disheartening fitting out a boat that just looks plain ugly. However that same length would look very nice, even beautiful if you built a replica Thames steam launch with a small, light inboard engine, useful, easier to make lightweight, very saleable, easily driven, and you would get lots of compliments. I would spend the winter doing lots of research. If you look at Selway Fisher designs you can see a few.

Edited by Bee
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regarding the weight if it becomes to heavy for a trailer i can always get it lifted and taken to the water by lorry.


According to the description, that eBay item is just the gearbox, not the engine...

yes it was the only pic i could find of the engine.

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There is a lovely 25 ft nb moored near to our house which is fitted with a 10hp vetus (it is currently for sale.) To my mind it is an attractive boat, but I doubt if it would be trailerable. Will get a pic later. If I was after a 25ft NB it would be/look like this one.

I found the advert for it here:

http://www.apolloduck.co.uk/advert.phtml?id=391837

Edited by Guest
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