GRP v Steel

[Shropshire Landlubber]

11 minutes ago, Tony Brooks said:

 

Not Tony's comment, it was magnetman.

 

We used to use coach bolts through the bracket and transom and then glass over the nut side. It would not stop the transom being cut away, and it was a bit of a task to take all the day boat outboards off at the end of the season.

 

You may well find that at 30hp the charging output is higher than smaller models, but probably nowhere what a modern domestic alternator would produce these days.

Apologies to you, Tony, and also to Magnetman - mis-read the header!  Seems that most of the 32 ft CC cruisers have 25 or 30 hp - modern outboards should produce sufficent output for careful use I guess but would depend upon decent batteries and regular running / cruising, like any other boat.  We are not heavy users of wiggly-amps and favour gas as much as possible on boats or caravans

 

So many choices, so many ideas - must be time for a glass of "rouge" whilst I ponder some more!

[David Mack]

6 hours ago, Barneyp said:

As GRP boats are not normally designed specifically for canals...

Most of the grp cruisers with 7ft or less beam are specifically designed for narrow canal use.  Cruisers built for use on rivers, lakes and the sea are generally wider beam as that provides more usable internal space.

[magnetman]

I really like the Norman Giles Mariner Boats. Never had one and they have a funny transmission which is likely to be problematic due to the age but they are nice Boats.

 

For narrow canals it is pretty difficult to beat a steel narrow Boat for a number of different reasons. 

 

As for theft of outboards it seems to be a bit random but sometimes it is organised and they just take everything. 

 

Inboards are more difficult to steal although I do know someone who had their inboard engine stolen from their traditional style narrow Boat which they lived on. Moored too near a dodgy road someone watching behaviour came and lifted it one day. 

 

Outboards are a well known theft item. Bolting through the transom is a Good Idea and yes it is normally the smaller ones. 

 

[Barneyp]

1 hour ago, David Mack said:

Most of the grp cruisers with 7ft or less beam are specifically designed for narrow canal use.  Cruisers built for use on rivers, lakes and the sea are generally wider beam as that provides more usable internal space.

I disagree, there are a lot of GRP with a 7ft beam for narrow canal use AND a hull which is clearly designed to plane at speed i.e. not on a canal.

Most Norman boats have a beam for narrow canals and are also suitable for use on Rivers and costal waters. And lots of Shetland, Viking and other manufacturers boats are similarly designed. There were GRP boats built specifically for canals in the 60's and 70's, but once steel narrowboats became the preference, it wasn't worth producing boats for such a small market.

[David Mack]

41 minutes ago, Barneyp said:

I disagree, there are a lot of GRP with a 7ft beam for narrow canal use AND a hull which is clearly designed to plane at speed i.e. not on a canal.

Most Norman boats have a beam for narrow canals and are also suitable for use on Rivers and costal waters. And lots of Shetland, Viking and other manufacturers boats are similarly designed. There were GRP boats built specifically for canals in the 60's and 70's, but once steel narrowboats became the preference, it wasn't worth producing boats for such a small market.

The boats you have listed were mostly built with the canal market in mind, which is why they were built to 6ft 10in beam. Which isn't to say they weren't also interested in selling them to other markets. And given their eye on a range of markets, it isn't surprising that they selected hull forms which could be used in a range of different conditions. Just because some of those hulls are suitable for planing doesn't make them unsuitable for use on canals, as evidenced by the large number that were used on the cut in the 1960s and 70s, before the rise of the steel leisure narrow boat.

[Barneyp]

7 hours ago, David Mack said:

The boats you have listed were mostly built with the canal market in mind, which is why they were built to 6ft 10in beam. Which isn't to say they weren't also interested in selling them to other markets. And given their eye on a range of markets, it isn't surprising that they selected hull forms which could be used in a range of different conditions. Just because some of those hulls are suitable for planing doesn't make them unsuitable for use on canals, as evidenced by the large number that were used on the cut in the 1960s and 70s, before the rise of the steel leisure narrow boat.

I didn't say that having a planing hull made boats unsuitable for canals.

I did say that a planing hull and/or shallow draught often leads to GRP boats having either quite a high Air draft or low internal cabin height in comparison to steel narrowboats.

That doesn't make them unsuitable for canals, it was just something for the OP to be aware of.

11 hours ago, Shropshire Landlubber said:

Apologies to you, Tony, and also to Magnetman - mis-read the header!  Seems that most of the 32 ft CC cruisers have 25 or 30 hp - modern outboards should produce sufficent output for careful use I guess but would depend upon decent batteries and regular running / cruising, like any other boat.  We are not heavy users of wiggly-amps and favour gas as much as possible on boats or caravans

 

So many choices, so many ideas - must be time for a glass of "rouge" whilst I ponder some more!

 

A lot of canal based GRP boats seem to have very oversized outboards.

When I was getting an outboard for my canal based GRP boat I was advised not to get too big an outboard as that would lead to it running at near tickover most of the time, and it was better for the outboard to be run at higher revs.

25 -30hp on a viking 32 is quite a lot for narrow canal use, and even if the outboard has the capacity to charge batteries, if you only ever run it at low revs it may not produce much charge.

Probably best to ask on the Vikings Owners website or Facebook page.

[magpie patrick]

9 hours ago, Barneyp said:

I disagree, there are a lot of GRP with a 7ft beam for narrow canal use AND a hull which is clearly designed to plane at speed i.e. not on a canal.

Most Norman boats have a beam for narrow canals and are also suitable for use on Rivers and costal waters. And lots of Shetland, Viking and other manufacturers boats are similarly designed. There were GRP boats built specifically for canals in the 60's and 70's, but once steel narrowboats became the preference, it wasn't worth producing boats for such a small market.

Viking still make them so obviously it is worth "producing boats for such a small market"

51 minutes ago, Barneyp said:

I didn't say that having a planing hull made boats unsuitable for canals.

I did say that a planing hull and/or shallow draught often leads to GRP boats having either quite a high Air draft or low internal cabin height in comparison to steel narrowboats.

That doesn't make them unsuitable for canals, it was just something for the OP to be aware of.

 

A lot of canal based GRP boats seem to have very oversized outboards.

When I was getting an outboard for my canal based GRP boat I was advised not to get too big an outboard as that would lead to it running at near tickover most of the time, and it was better for the outboard to be run at higher revs.

25 -30hp on a viking 32 is quite a lot for narrow canal use, and even if the outboard has the capacity to charge batteries, if you only ever run it at low revs it may not produce much charge.

Probably best to ask on the Vikings Owners website or Facebook page.

I agree with all that. For information, Juno is a Viking 23 and has always had a 10hp engine, easily big enough unless you want to stem the tide in the Avon Gorge.

 

Can I add, it would be helpful if those of us who do own grp cruisers weren't frequently contradicted by some posters who clearly do not. Some of the things said about GRP cruisers above can only come from people who've never had one.

 

GRP cruisers are economic and practical - I'd have given up boat ownership long ago if narrow boats were the only option. Even a 23 foot steel narrow boat would cost far more to run over, say, ten years, than a fibreglass cruiser does. 

[Barneyp]

4 minutes ago, magpie patrick said:

Viking still make them so obviously it is worth "producing boats for such a small market"

But most viking boats are not produced just for the "small market" of narrow canals, they are also suitable for rivers, estuaries and possibly coastal waters.

I accept what I'm saying is a generalisation and there will be some exceptions.

My main point was that a lot of narrow beam GRP boats were not designed solely for canals so there are some compromises in the design, e.g.. around cabin height and air draft.

[David Mack]

2 hours ago, Barneyp said:

I didn't say that having a planing hull made boats unsuitable for canals.

I did say that a planing hull and/or shallow draught often leads to GRP boats having either quite a high Air draft or low internal cabin height in comparison to steel narrowboats.

It's not the hull shape or material that makes grp boats sit high in the water and hence have low cabin height or high air draft. It's the fact that they are not ballasted down as steel narrow boats are. A bare narrow boat shell without any ballast only draws a few inches! It takes a diesel engine plus a few tonnes of bricks, paving slabs or steel to bring it down to the depth/height usually seen. There's no reason why you couldn't do the same with a grp boat; it's just that the designers and builders of such craft have chosen not to do so.

On most grp cruisers the highest point which determines the  air draft is a fixed windscreen on the cabin top. That may have a function when you are speeding through spray on open water, but isn't actually needed when canal cruising. It would be perfectly possible to do away with the windscreen and provide a higher cabin top to give the same air draft and more internal headroom. I suspect the reasons this isn't done are down to aesthetics and the increased sensitivity to wind that would result.

[magpie patrick]

22 hours ago, Barneyp said:

As GRP boats are not normally designed specifically for canals they  tend to float higher in the water and/or have a v hull.

 

This means that in order to get a reasonable internal cabin height the air draft is to high to fit through some tunnels and bridges, or in order to keep the air draft down you can't stand up in the cabin.

 

 

The basic premise here isn't accurate - Juno has probably the best internal headroom of the boats I've owned, yet her cabin isn't significantly higher than a modern narrow boat. However there is much less boat "under the floor" than on a narrow boat - no stretchers, bearers or ballast - so you feet are only an inch above the water underneath in places. Add to that the gap between the ceiling and the roof is less (less insulation) and there is good headroom without excessive cabin height. The price for this is that it's colder in winter!

[magnetman]

2 hours ago, David Mack said:

It's not the hull shape or material that makes grp boats sit high in the water and hence have low cabin height or high air draft. It's the fact that they are not ballasted down as steel narrow boats are. A bare narrow boat shell without any ballast only draws a few inches! It takes a diesel engine plus a few tonnes of bricks, paving slabs or steel to bring it down to the depth/height usually seen. There's no reason why you couldn't do the same with a grp boat; it's just that the designers and builders of such craft have chosen not to do so.

On most grp cruisers the highest point which determines the  air draft is a fixed windscreen on the cabin top. That may have a function when you are speeding through spray on open water, but isn't actually needed when canal cruising. It would be perfectly possible to do away with the windscreen and provide a higher cabin top to give the same air draft and more internal headroom. I suspect the reasons this isn't done are down to aesthetics and the increased sensitivity to wind that would result.

There are not all that many GRP Boats around which have vertical sides and full width flat bases though. Even the accommodation-focussed broads cruisers tend to have a Boat shaped hull rather than a brick shaped hull. 

 

[BilgePump]

46 minutes ago, magnetman said:

There are not all that many GRP Boats around which have vertical sides and full width flat bases though. Even the accommodation-focussed broads cruisers tend to have a Boat shaped hull rather than a brick shaped hull. 

 

Maybe because it's easy to fab an extending (sacrificial) edge from the baseplate in steel but wouldn't work in GRP. The structural strength of things made in brute force steel sheets vs the advantages of curved structures resisting pressures in GRP? Those bathyspheres look like a giant marble, not a brick or tubular Titan.

[Mad Harold]

It all comes down to costs.

GRP boats are much cheaper to buy and maintain than steel boats.If you live aboard,  a steel narrowboat is a much better bet, as they will (usually) come equipped with hot water, heating, insulation and standing headroom, plus they are easier to get on and off than most GRP cruisers.Looked at one GRP boat with a view to buying, (a Mayland Saphire) but the gunwale was almost chest high and I thought I would need a block and tackle to get out when single handed.

A GRP cruiser I think is fine for hobby boaters and to me at least look much nicer than a skip with a pointy end, but I will readily admit that a steel narrowboat is a superior vehicle for cruising the narrow canals.

The OP said they would prefer a modern GRP boat, but the old Normans and other boats from the sixties and seventies were built from thicker layups than modern ones, and as GRP lasts indefinately an old GRP boat can be a good buy.

[max campbell]

We had a Viking 28 narrow beam for 8 years. We liked sitting down and looking forward when cruising, but we couldn't put up with the outboard any more - carrying jerrycans from petrol stations is horrible, and a constant worry. Also the very limited electric output was limiting for fridge use, etc. Then there's the high cockpit coaming to climb over going in and out.

 

So we got a Sea Otter centre cockpit, with an inboard diesel. I would prioritise an inboard diesel over all other considerations - there are a very few inboard diesel narrow beam GRP boats. There aren't many Sea Otter centre cockpits.

 

The difference in draft or airdraft between steel & GRP is not significant.

Further to my last, and on reflection, diesel is a high priority for us because we tend to do longish trips - 2 to 3 weeks. If you're going to just go for weekends, then you can fuel up at your home berth before each trip.

 

An outboard gives you far more manoeuvrability, because you can direct forward and reverse thrust in any direction, it's very easy to control direction in reverse, twiddle in almost your own length, etc.

[Stroudwater1]

7 hours ago, Mad Harold said:

It all comes down to costs.

GRP boats are much cheaper to buy and maintain than steel boats.If you live aboard,  a steel narrowboat is a much better bet, as they will (usually) come equipped with hot water, heating, insulation and standing headroom, plus they are easier to get on and off than most GRP cruisers.Looked at one GRP boat with a view to buying, (a Mayland Saphire) but the gunwale was almost chest high and I thought I would need a block and tackle to get out when single handed.

A GRP cruiser I think is fine for hobby boaters and to me at least look much nicer than a skip with a pointy end, but I will readily admit that a steel narrowboat is a superior vehicle for cruising the narrow canals.

The OP said they would prefer a modern GRP boat, but the old Normans and other boats from the sixties and seventies were built from thicker layups than modern ones, and as GRP lasts indefinately an old GRP boat can be a good buy.

 

In what way is a narrowboat superior for cruising the narrow canals?  many do come with hot water, often instant, plus good headroom? Getting on and off is not difficult unless you are arthritic, there is an art and you need to get used to your boat, but thats true for NBs too. Manoeuvrability is much better in a GRP boat as it mooring availability. 

 

If we are talking of creature comforts possibly so, but even then not by that much in a decent GRP or wooden cruiser. 

 

 

[Ewan123]

7 hours ago, Mad Harold said:

GRP lasts indefinately

Surely so can steel if it's maintained very well. I thought GRP can suffer 'osmosis' which weakens it?

Edited January 25 by Ewan123

[Mad Harold]

18 hours ago, Ewan123 said:

Surely so can steel if it's maintained very well. I thought GRP can suffer 'osmosis' which weakens it?

Had two GRP cruisers both made in the seventies with no sign of osmosis on either.

Perusing other boaty forums, it seems to be a rare occurance but takes the form of 'bubbles' in the gel coat.The repair seems to be cutting these 'bubbles' off, allowing the hull to dry out and use gel coat filler, sand and paint. General opinion has it that these 'bubbles'are caused by poor build quality control, possibly moisture in the initial layup.Scratches in the gelcoat if untreated can cause osmosis by allowing water into the fibreglass, and if a large enough area, can weaken the structure.

18 hours ago, Stroudwater1 said:

 

In what way is a narrowboat superior for cruising the narrow canals?  many do come with hot water, often instant, plus good headroom? Getting on and off is not difficult unless you are arthritic, there is an art and you need to get used to your boat, but thats true for NBs too. Manoeuvrability is much better in a GRP boat as it mooring availability. 

 

If we are talking of creature comforts possibly so, but even then not by that much in a decent GRP or wooden cruiser. 

 

 

Had two GRP cruisers and a steel narrowboat so am giving my opinion.

I cruise singlehanded so that has coloured my opinion.

In the GRP boat, you moor at the lock landing, climb out, set the lock, back to the boat, climb in, into the lock, climb out, fill or empty the lock, climb in, out of the lock, climb out, close lock gates, back to the boat and climb in.

This is fine for the first dozen or so locks, but does become quite fatiguing.I did have 'mounting blocks' but it was still necessary to step up and down.

The narrowboat was much easier in that you only needed to step on and off.

The other reason I thought the steel narrowboat was a better vehicle for narrow canals (apart from them usually being better equipped with  creature comforts) was the handling.

All boats are of course affected by wind, but the GRP boats being more on the water than in it, and light weight for their size, in windy conditions you couldn't take your attention off the steering for long as they tend to wander.The narrowboat, once underway was much more directionally stable due to it's weight and deeper draught.

 

[David Mack]

The real issue for the OP in this thread is not what material the boat is constructed from, but what style/shape/length of craft he wants. 

[Ewan123]

On 26/01/2024 at 14:53, Mad Harold said:

Had two GRP cruisers both made in the seventies with no sign of osmosis on either.

Perusing other boaty forums, it seems to be a rare occurance but takes the form of 'bubbles' in the gel coat.The repair seems to be cutting these 'bubbles' off, allowing the hull to dry out and use gel coat filler, sand and paint. General opinion has it that these 'bubbles'are caused by poor build quality control, possibly moisture in the initial layup.Scratches in the gelcoat if untreated can cause osmosis by allowing water into the fibreglass, and if a large enough area, can weaken the structure.

Interesting to know, thanks 👍

On 26/01/2024 at 17:43, David Mack said:

The real issue for the OP in this thread is not what material the boat is constructed from, but what style/shape/length of craft he wants. 

 

Yes, I think the original post was based on the misconception that steel boats are all the same, as are GRP boats; and although a majority of each follow a pattern, if one can take the time to look around, there are many varieties of each out there. We could even say that there's a greater variety of steel boats available to suit all needs.

[Shropshire Landlubber]

Does anyone have experience of the Crieghton 32 cruiser please, in particular the reliability of the inboard engine and outdrive setup, or any issues with osmosis / construction etc ?  The layout with the rear deck space really appeals to me but I realise that they are all pretty old now and could be a heap of problems unless have been well looked after.

I've seen a couple for sale, hence my thirst for a little more knowledge if anyone has any before I follow up.  Thank you

[Tony Brooks]

1 hour ago, Shropshire Landlubber said:

Does anyone have experience of the Crieghton 32 cruiser please, in particular the reliability of the inboard engine and outdrive setup, or any issues with osmosis / construction etc ?  The layout with the rear deck space really appeals to me but I realise that they are all pretty old now and could be a heap of problems unless have been well looked after.

I've seen a couple for sale, hence my thirst for a little more knowledge if anyone has any before I follow up.  Thank you

 

You may need to tell us make and model of engine, and ditto for the outdrive.  Diesel or petrol engine as well, because if it is petrol you will be carrying it cans for refuelling on a lot of canals. If the outdrive is an Enfield Z drive then they tend to be agricultural and fairly reliable once they are got into good condition. If it is anything else, it may be far more complex.

[Shropshire Landlubber]

3 minutes ago, Tony Brooks said:

 

You may need to tell us make and model of engine, and ditto for the outdrive.  Diesel or petrol engine as well, because if it is petrol you will be carrying it cans for refuelling on a lot of canals. If the outdrive is an Enfield Z drive then they tend to be agricultural and fairly reliable once they are got into good condition. If it is anything else, it may be far more complex.

Thank you Tony - that's the sort of info that I'm trying to find out tbh !  I've found very little info and want to know what I should expect if we go to look at any that come up for sale.  From images I've found, at least one has some sort of Z drive (I think) but as yet I've find nothing to verify "standard" engine / propulsion.

[Tony Brooks]

1 minute ago, Shropshire Landlubber said:

Thank you Tony - that's the sort of info that I'm trying to find out tbh !  I've found very little info and want to know what I should expect if we go to look at any that come up for sale.  From images I've found, at least one has some sort of Z drive (I think) but as yet I've find nothing to verify "standard" engine / propulsion.

 

That is because with boats, especially older boats on the inland system absolutely nothing is standard. The Creightons probably cake with alternative options. Ford OHV petrol engines were popular, as were BMC 1.5 diesel or Perkins 4-10x engines. Plus, we have no idea what subsequent owners have done. You might even strike lucky and find one that has had an engine change for something more modern, but on the other had you could just as easily find one with a badly marinised "van" engine done is Fred's shed.

 

In any case, engine and outdrive wise, wear is likely to be a major concern nowadays because of age. If it is a diesel and it starts easily from cold with only a little exhaust smoke that soon clears, it is probably not too bad, especially if its hot oil pressure is over about 35 psi when revving and above about 15 psi on idle.

[magnetman]

Old Z drives are a bit of a nightmare. 

 

The gearchange dog clutches go and they sometimes whine terribly. 

 

I would much rather an outboard also with an outboard you get a bit more space in the actual Boat. 

 

 

 

It is feasible to find a Boat with a nackered inboard and Z drive then get the transom rebuilt and put an outboard on it. 

 

Modern 4 stroke outboards are lovely and quiet and also economical but of course petrol is generally more expensive than red diesel and harder to get canalside. 

 

It depends on the intended running hours.

 

 

[Tony1]

1 hour ago, magnetman said:

 

It is feasible to find a Boat with a nackered inboard and Z drive then get the transom rebuilt and put an outboard on it. 

 

Modern 4 stroke outboards are lovely and quiet and also economical but of course petrol is generally more expensive than red diesel and harder to get canalside. 

 

 

I'm reading these posts with interest because in the longer term I would consider getting a viking 32cc or similar, especially if I find I'm struggling to handle a steel narrowboat.

I was thinking a GRP might be the logical choice when one starts to lose strength and mobility, but clearly there can be some issues climbing in and out of them- although having a section of the side wall cut out does seem feasible.  

 

I like your idea of fitting an outboard, if its an old boat with an unreliable inboard diesel engine, and especially if the hull is still in very good condition etc (and the interiors could be refitted on a DIY basis if that hasn't already been done).

 

Diesel outboards are just too expensive, and the hassle of fetching petrol once or twice a week is a concern, but I would be using an ebike so not too much hard work involved.

And if one could fit panniers that hold a 10L jerrycan on each side, one could fetch 20 litres in a single trip. 

The problem of getting a good battery charge in winter is also a concern with an outboard, so a genny would probably be needed for part of the year, depending on how much solar could be fitted. 1000 watts would go a long way to reducing reliance on a genny.

 

 

Edited February 14 by Tony1