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Building An Aluminium Narrowboat – Part 1

Early June 2010

I’ve had one narrow-boat, a 55′ cruiser-stern Liverpool Boat.  I did a great deal of work on that, most of it involving rust removal or rust prevention, and I found that my efforts would need to be ongoing if it was to remain in reasonable condition.  The worst two jobs were the bottom-blacking every two or three years (combined with the associated replacement of anodes), and the painting of the inside of the steel water-tank, without doubt, in my opinion, the very worst chore.

I decided on a change of boat last year.  There were to be two priorities.  With a grand-child imminent, I wanted a “semi-traditional stern”, which provides a safer haven for youngsters than a cruiser stern.  And with older age imminent, I wanted less maintenance work.

A visit to Sea Otter at Staveley, (between Chesterfield & M1) in early July 2010 seemed like a good idea.  They build narrow-boats out of marine-grade aluminium alloy.  So no rust and no blacking.  No electrolytic action below the waterline ( * ) so no anodes to replace.  And with a stainless steel water tank, no painting.

( *  There are no dissimilar metals in contact with the hull below the waterline on a Sea Otter Boat.  All stern gear runs through a phenolic cutlass bearing. The stainless rudder and stock run through MDPE bearings. Any below-the-water-line fittings that may be dissimilar are fitted with a polyurethane gasket. None of these conduct electricity. Because there are no dissimilar metals in close proximity, no electrolysis can occur.)

In early June 2010 I met up with brothers Anthony (who I had earlier met at the Birmingham Boat Show) & Paul, who now run the business between them.  It was started by their uncle 17 years ago.

After preliminary discussions with them, and an inspection tour of their brand-new-looking factory, paint-shop, test-tank, and kitchen / bathroom fabrication unit, I was impressed, and had confidence in them.  Alnost everything is made “in-house”.

I am given a basic price for a 56′ semi-trad. They’ll give me a lifetime guarantee on the hull.  What are they trying to tell me ?

Everything considered, including the reported very low level of depreciation, the price seemed reasonable.  It incorporates some items that, from other boats-builders, may be charged as extras, such as bow-thruster, shore-power, navigation lights, immersion heater, bathroom & kitchen extractor fans, stainless steel water-tank, water & diesel tank gauges, Hospital Silencer, Anchor etc etc.  Quite a few items could be deleted from my “wish-list” that I had taken along with me, and Anthony & Paul did me a few good deals on some of the remaining ones.

But the list still included some additional expensive bits, such as a Morso Squirrel Stove, a 240V transmission (“intercalated”) generator for the Nanni engine, heat-trace freeze-protection for the cold-water system, Axiom propeller, and a side-hatch.  We reckon £125,000.00 will cover everything.  There are boats being made at that price that’ll soon start rusting.

The next stage was the signing of the purchase form, designed by the “British Marine Industries Federation” and approved by the RYA.  It protects both sides.

I’m pleased to be told that I’ll be supplied with a Boat Safety certificate on completion !

The final stage that day was the paying of a 20% deposit on the base price.

The second instalment (30%) will be due upon completion of hull fabrication, estimated to be end of December 2010.

The third instalment (another 30%) will be due upon installation of engine & cabin-lining, estimated at end of January 2011.

The final instalment (20% + extras) will be due upon completion of construction prior to boat leaving factory, estimated at mid to end of March 2011.

21st July 2010

I return to Sea Otter with a plan:-

1)  My plan

My plan was very approximately to scale, on A3 graph-paper, and amply decorated with post-it-notes!  That way I could shuffle sections around, and re-draw them independently when necessary.  The scale of the boat on the graph paper was very approximately 1 inch equals 2 feet.  I had just roughly divided the length into 9 sections which looked about right in relationship to each other :-  bow, fore-deck, lounge, dinette, kitchen, bathroom, bedroom, rear-deck, and finally the back-end.  No technical terms here, but generally considered to be of a “floating-cottage design”.   Anthony is going to transform my efforts into a more acceptable form with the help of a computer and a printer.

In the short time since my last visit, the marine-grade aluminium alloy sheets for my boat had arrived, and were neatly stacked up in the factory !

2) Aluminium

The big suckers above the stored aluminium sheets facilitate the raising, rotation & transportation to different areas of the factory during construction.There are two thicknesses shown.  8mm for the base-plate and sides up to gunnels.  6mm for the sides above gunnels & roof.    But the hull is actually better protected than those figures might suggest.  There is an additional v-shaped hull constructed of 6mm aluminium alloy below the 8mm base plate.  That makes a total of 14mm of protection under the boat.

The aluminium alloy is delivered in 12 metre lengths, so there will only be one vertical join in the entire length of the boat.

I had a few pre-conceived ideas about my boat.  Following discussions at this early stage, some of my ideas were about to change, and I get my own way on others.

I originally wanted my batteries to be easily accessible, preferably in a locker from which they could be easily removed for maintenance.  In my old boat it was a back-breaking job to remove the batteries for water-level-checking.  But Paul tells me that he’d be supplying Vetus 108AH sealed-gel batteries which shouldn’t need maintenance of any description for several years.  We read an article published in a canal magazine about a guy who had 3 such batteries in his boat for 20 years, and they were still going strong when he sold it !  Then Anthony told me that a battery monitor would be fitted.  I’m then informed that the dreaded boat inspector can be very fussy about where & how batteries are stored.   And that Paul has just taken delivery of some very nice new and specially designed fibre-glass battery boxes.  I capitulated. The batteries will be hidden away in the engine bay.  (1 to them)

I had a preference for the calorifier to be in the bottom of an airing cupboard.  I reckon this is the best place for it, because the heat from it isn’t wasted (it helps to dry clothes) and the hot water within keeps warmer longer.  Anthony & Paul explain that the new calorifiers are so well insulated that they don’t loose much heat.  [I find out later it’s not just the heat from the calorifier that helps dry my clothes, it’s the heat from the several pipes running to and from it.] They prefer the calorifier in the engine bay because if it ever leaks, the water just runs harmlessly into the bilge. Fair point, but then I learn that it may well be necessary to remove the engine to replace a faulty calorifier !   I get to keep it in the airing cupboard.  (1 each)  [I live to regret that decision!]

Don’t get me wrong.  They’re quite happy to do almost anything to a boat to suit the buyer.  But they’ll input the benefit of their experiences and leave the final decision to the buyer.  I’d be daft not to listen.

Anthony & Paul showed me one of their boats being built, to examine the kitchen & bathroom.  Both varied a little from my pre-conceived ideas, but the differences were unimportant, they know their ideas work, so I go with the flow.

So ended my second fruitful visit to Otter Boats, and I look forward to seeing my computer-generated boat-plan at my next visit, leading to more discussions about the details.

27th OF OCTOBER 2010

Back in the Sea Otter office I get to see my boat’s computer-generated plan he’d been working on.

3)  Computer plan


There’s plenty to discuss.

My engine bay (and hence the boat) has to be made a little longer to incorporate the extra length of my Nanni engine because of the addition of the aforementioned “intercalated generator”  This is a nice bit of kit, though pricey at about £2.5 grand.   It is round, like a pancake, and fits between the engine and the drive shaft, and produces 230V as the engine runs.  The obvious advantage of this over the Electrolux “Travel-power” system that was fitted to my previous boat, is that “the pancake” is maintenance-free….no expensive poly-v belts to replace every couple of years.  [ I find out later that there are disadvantages to this as well ! ]

Sea Otter Boats fit a Webasto diesel heating system by default.  I’ve had problems with another popular make in the past, so I’ll be happy to go along with this.

There are to be 5 radiators throughout the boat, and a heated towel rail in the bathroom. Two of the five radiators are to be in the lounge.  That’s one more than Sea Otter normally fit.  They will do calculations to decide if a larger than usual calorifier will be necessary.

I am shown 3 samples of kitchen worktop, and a quick decision is made on which it is to be.

I like windows rather than portholes, for the extra light they provide, but it’s to be portholes in the bedroom on the port side, and in the bathroom (same side).

The windows recently fitted to Sea Otter Boats have had curved tops, which I quite like.  But I have a preference for bigger ones.  I also specify an opening hopper top, because they can be left open for ventilation when it’s raining.  And I also specify sliding windows below the hopper top.  It seems to me that they provide better ventilation.  All these windows will need to be specially ordered, which Paul is happy to do.

I like carpets fitted up to the gunnels.  It takes some nerve to write that because it’s an old fashioned idea.  But I think it makes the interior cosy.  Does it improve the general insulation of the boat ?  It must, and by a good amount I would think.

I had decided on a cassette loo.  I’ve had a pump-out loo, and personally I wouldn’t have one again, because of unpleasant blockage problems experienced.  In many respects this boat is to be kept as simple as possible.

I order a side-hatch opposite the kitchen.  It is to be glazed, so, just like a window, it lets in light even when closed.

The subject of insulation had cropped up on several occasions, and I had done a bit of my own research.

I looked at “Thermafleece”.  As the name suggests it is made from a sheep….compressed wool.  At about £5.00 per square metre the price compares well to “Thinsulate” at £20.00 per square metre.   But a technical consultant told me that the former will allow moisture in, and if it can’t escape effectively (and how could it on a narrowboat) the water could cause deterioration in the product, and eventual degradation.  So that’s off the list of possibilities.  Sea Otter Boats usually fit sheet foam.  They’re used to fitting it, and they’re good at fitting it.  They’ve built a lot of boats with it, without problems, and without complaints.  Anthony & Paul say “if it ain’t broke, don’t try to fix it”.  They do offer the alternatives of fitting “Thinsulate”, or “getting the spray-foam-boys in”, both at additional cost off-course.  I decide again to go with the flow.  I decide that foam sheets will do fine.

An experienced friend of mine is adamant that holes should never be cut in the roof of a boat unless absolutely necessary!  But I like roof-hatches, Houdini-hatches, and even prisms.  But my good friends’ words echo in my ears every time any of the above are considered. I end up not ordering any, consoling myself with the thought that I have lots of big windows to let light in, the side hatch will be glazed, all the interior wood is light in colour, and that a cream vinyl headlining is to be fitted as part of the Sea Otter package.

There’ll be no cratch !  I think the bow is the very nicest part of the boat to sit in. You’re transformed to a different world.  It is a quiet vantage point.  You’re the first to see birds & animals.  You’re the first to get there.  I think a cratch takes something away.  The cratch was the first thing I removed from my previous boat.

We decide on stable doors at the bow.  These enable full-length lockers to be built along the sides of the fore-deck which double up as seats.  The lower sections of the stable doors open against the locker sides utilising magnetic catches to retain them, and the upper halves of the stable doors open right across, to lie against the front bulkhead, and you can lean back against them.

I have “trace heating” in bold type on my wish list.  I think it is a great concept.  It protects your water-pipes from freezing, avoiding the hassle of draining water systems down prior to leaving your boat in the winter.  “Trace heating” is simply a special flattish wire, (looks like “twin & earth”) which is attached (using cable-ties) to the water pipes.  (You don’t fit it to the radiator pipes because they are already protected by having anti-freeze inside them.)  When the temperature drops to near freezing a thermostat clicks on and the wire warms up ! Wonderful.  It will be easy to fasten the wire, comparatively speaking, during the plumbing installation stage.  I fitted a similar system retrospectively to my last boat and it took many hours of work.

I reckon when operating it will use about 420 watts of electricity.  It will cost about £500.00 for this 57 foot boat.  Not bad for the peace of mind it will provide over many hard winters.  Disadvantages ?  …..you need a very reliable supply of shore-power right through the winter !

I’ve only been at Otter Boats for a couple of hours, but many important decisions have been made.  Because of a trip abroad, I won’t be back until after the building of my boat begins, estimated to be mid November.  The first stage will be the construction of the “V” hull.

The “V”  hulls of Sea Otter Boats are designed to let water in.

More about that, and photographs of the various build stages which follow, in part 2.

Useful Information
Paul Smith

After six and a half years living on a narrowboat on England's inland waterways, Paul and his wife Cynthia now wander Europe by motorhome during the winter, and on the Dutch and French waterways in the warmer months on their 32' Dutch motor cruiser.