Log in
Article search:

Q & A

Hight and Draft

Dear Sir,
I am looking at buying a new narrow boat (sail-away). Problem is that I am 6' 7" tall with shoes. I do not wish to duck my head other than the odd roof light.
Can a boat be made that can still navigate all the waterways and not 'beach' its self on root or get wedged under any bridges?
Please no jokes, herd it all before. Otherwise I will have to start on the short people jokes.
Yours Faithfully
Mr G. Dean

Asked by: Gary  | 1.10am, Wednesday 11 July

WW says:

It is certainly possible to build a boat with greater than usual headroom inside, there will however need to be some compromises.
The majority of sail away shells have sufficient headroom inside to easily accommodate 6ft tall persons. They usually have a draught of around 20 inches; by increasing the depth to 30 inches will give you more headroom without altering the navigable range. The difference in depth will make steering slightly harder and will limit mooring spots. If the cabin height is increased this will definitely restrict the cruising range, whereas increasing the depth of the boat will not since the canals were built with plenty of water.
You will need to commission a shell to be built to your specification, as merely increasing the height of the cabin will produce an unwieldy craft with a restricted range.

Rupert Smedley  | 9.35AM, Wednesday 11 July

Also, when fitting out a boat, it is possible to reduce the space taken by insulation and ballast, which in turn allows you to have greater headroom in any given shell.
Instead of the more standard spray foam insulation, which tends to be around 50mm or so thick, you coulda use a material such as 3M'sThinsulate- which has a low U-value, is thin and can be adhered directly to the shell with contact adhesive- this has been done successfully with several boats.
Also, the wooden noggins (battens) that the lining material is fixed to the cabin side can be made thin, and for the cabin roof, thinner than usual lining materials- such as strong faced plywood can be used to gain a few mm. As long as there is an air gap and there is no direct contact with the steel and the lining material, you should be fine.
If a thicker than usual baseplate is specified- say 12, 15 or even 20mm, then the amount of ballast required to pull the boat down in the water can be reduced. Any remaining ballast can be in the form of dense steel or lead ingots, placed away from the walkways, with raised bases to cupboards, under berths, etc.
As long as there is still an air gap under the flooring- and preferably good underfloor ventilation, you might be able to gain around 4 to 6 inches by being careful with the planning, without having to make the exterior of the boat ungainly, or the draught too deep, as Rupert explains. By adding a few inches to the draught and to the cabin superstructure, you should be able to design a boat that fits your requirements. A discussion with a boatbuilder or even a marine surveyor, might be able to produce a good design that you can then fit out to suit your needs.

Mark Langley  | 10.48AM, Wednesday 11 July

I was on a brand new boat today which has a depth of 20 inches, and the headroom in the cabin was 6ft 4".
So to gain another 4 or 5 inches to give you sufficient headroom is not particularly difficult; the difference in navigating a boat with a draught of 2 ft is negligible. there are plenty of boats around with 3ft draught.
If you talk to a reputable shell builder they will have the expertise to be able to help with the design, without the extra expense of a marine designer.

Rupert Smedley  | 6.18PM, Friday 13 July

IF you look at the fuel consumption charts of the Beta 43, at canal cruising speeds (around 1300 to 1400RPM) you would expect to be using 1 to 1.5 litres an hour cruising. Narrowboats use larger engines that might be first considered sensible, but this is for a number of good reasons. Firstly, slower running means quieter, and less stress on the engines. Also, a smaller engine doesn't have the torque to both propel and, more importantly, stop a boat. A larger engine running slowly uses far less fuel than a small engine running quite fast- as you can see from the fuel consumption curve of an engine.
However, for a 52ft boat, a slightly smaller engine will be fine- like the 35hp, 1400 engine. Running faster does reduce the chances of oil sludging, while still having reserves for river cruising.
As for diagnostic electronics- these are never fitted to inland engines! Some larger river and sea going boat engines use them, but they are irrelevant to inland boats- as long as you know the oil pressure and engine temperature, that is all the monitoring information that you need.
Most modern narrowboat diesel engines are based on small agricultural, or stationary (generator) units and so do not carry the electronic Euro V controls required for automotive road engines, so the emissions are kept with certain parameters.
This means that they are easy to service- however, all engines need to be kept supplied with clean, dry fuel, aligned and mounted properly (and checked anually), decent ventilation and coolant kept topped up with appropriate antifreeze solution.
Any modern narrowboat engine will give good service if looked after. Trying to marinise an automotive engine from a modern vehicle would be expensive and wouldn't give good service, as the slower speed running would shorten the life of the engine considerably. They are also far more complicated than the Vetus, Canaline, Beta, Lister, Barrus and Bukh engines that are fitted to most of the new boat market.
However, older, traditional engines, such as Russel Newburys actually use less diesel fuel (which isn't quite the same as DERV, by the way, as that is no longer produced as such)than modern engines, especially when running slowly.
You are right in the hull shape being important- narrowboat bows are not always the most efficient, but if you stray away from convention, you will find that the boat will be quite dificult to sell on in the future. The length of swims is important, but also how they taper in. Better quality shell builders pay close attention to the underwater shape. Fine terminations to aft swims, as well as double curvature, etc. are conducive to good handling, but come at an expense. From looking at different shell builders, and trying out as many boats as you can, you will find those that have good handling characteristics.
Hope that helps- for more information, see the Narrowboat Builders Book and the Inland Boat Owners book, which has more information. Do let us know if we can help futher.

Mark Langley  | 9.02PM, Saturday 14 July

I should add that Rupert will be the best person to answer about the chimney! Sounds an interesting idea though- much like on some FMC steamers, I think!

Mark Langley  | 9.11PM, Saturday 14 July

There are no "Regulations" governing the size of boats, but common sense based on the size of the waterways intended to navigate. There are notable restrictions on some of the more interesting waterways, the Llangollen and Chesterfield are tight on width, and the Caldon is tight on headroom both in Stoke and at Froghall tunnel.
Your idea of raising the roof by the height of the chimney collar will not really gain much. This is because the collar is usually mounted at the side away from the highest point of the roof curvature, to ensure that it is no higher than absolutely necessary. It is for that reason I suggest making the boat slightly deeper in the water, and a thick base plate will help with the extra ballast requirement.
On working boats the chimney is beside the steerer, so it is easily removed for tight bridges. Steamers often had a hinged funnel, and this is certainly possible with a little ingenuity, but you will still have the diameter of the chimney as extra height above the roof. A telescopic chimney is an interesting idea that I think is new. Problems might be soot getting into the mechanism and jamming it and appropriate materials. Do let us know if you manage to make one.

Rupert Smedley  | 10.18AM, Sunday 15 July

Readers say:

Thank you Sirs', very much for your answers. This would be an interesting topic in the WW magazine. I hope we see more loaded cargo boats on the canals as I might need some help!
I think it would be advisable for me to have a marine surveyor to plan a boat for me as it should help the builder. I like the idea of a thicker base plate. Must keep the roof strong still. So if reducing the 'RSJ' in size and adding more of them to keep up the weight bearing on the roof may help, although I do not want to make it to heavy at the roof. I will have to dig out Mr Booths book as it may help me with other parts of the shell design. I best add I am local to the River Stort.
Look out for 'Bigwellies' Photos on Google earth in a week or two.

Gary  | 3.40AM, Friday 13 July

Thank you again Mr Smedley. I think then it would be feasible then to have a thicker base plate to add deeper draught (as I like the idea, also saves money in the longer term for re plating).
Is there any regulations to stop me from raising the roof from 'standard hight' using some of the hight that the chimney takes up? Or does the chimney on new builds today need a minimum hight? To overcome the problem of short ones could I fit a telescopic chimney [6'7" guy at back of boat who does not want a sooty face at end of day] that can be lowered by means of a looped cable from the chimney to the stern that runs around a small wheel with handle to lower/raise it as hinged chimneys may let the heavy rain in.
I was going to ask separately another Q. I will add it here. I am not wallowing in cash income. How much does it cost to run for example, 52 foot narrow boat with 30" draught with for example a well known engine like the Beta 43, per hour along a canal? I see the Beta 43 has 1999cc. That seems a large engine using a lot of derv. I would want to use the boat on rivers if necessary. Although wanting to keep the cost of running it down. I like the idea of an engine without an Electronic Diagnostic computer attached to it. Because one can do little to it without great cost for a man who can if a fault should develop. So on the one hand I want to keep the costs down but to do that new modern engines use less derv that puts servicing costs up and the cost of the new thing in the first place. :(
I had herd in the past the bow of (NB) are not a good shape for cutting through the water. Also a long swim ('V'bit) would be needed at the stern to get most out of the prop. So boat length is an issue.

Gary  | 12.54AM, Saturday 14 July

I think it is time now for reading and looking at some boats and asking some boat builders some questions. I have the books mentioned somewhere.
Thank you again
Rupert Smedley and Mark Langley.
Gary Dean
'Head of River Stort'

Gary  | 5.59PM, Monday 16 July

You must log in to post an answer.