Steel hull and GRP tops

[muddywaters]

I've seen a few boats with steel hulls and GRP roofs advertised on various sites and wondered how suitable these boats would be as a live aboard ?

 

A friend with a GRP cruiser on the Lancaster canal tells me GRP boats are hard to keep warm when the weather is cold

[craftycarper]

Never owned a steel boat but do have a grp one and have a few buddy,s with narrow boats can't really say there's much difference in the winter if the fire is on in both they feel the same the grp will probably outlast the steel bit but just check it's not a rotten wooden top that's just been glassed over also should be a bit cheaper to buy than a full metal one

[tony p]

It depends on your budget,

most grp topped boats are getting quite elderly now and an all steel properly insulated boat will be more comfortable in all weathers but with a decent stove / heating system you can live quite happily on any boat.

Bear in mind that grp tops require a lot more maintenance than steel and often develop annoying leaks around the roof/ hull joins/ windows and vents.

Also watch for careless past removal of interior bulkheads as these were often built in to help stabilise the structure.

Tony

[blackrose]

Bear in mind that grp tops require a lot more maintenance than steel and often develop annoying leaks around the roof/ hull joins/ windows and vents.

Also watch for careless past removal of interior bulkheads as these were often built in to help stabilise the structure.

Tony

 

Yes as Tony says, there are often leaks between the steel and GRP and these occur as a result of the different thermal expansion and contraction rates of the materials.

 

For a liveaboard I'd say an all steel boat is a better bet. There are well insulated all GRP boats of course, but most were not designed for living on in winter and there are probably many more well-insulated all steel boats.

[Naughty Cal]

I've seen a few boats with steel hulls and GRP roofs advertised on various sites and wondered how suitable these boats would be as a live aboard ?

 

A friend with a GRP cruiser on the Lancaster canal tells me GRP boats are hard to keep warm when the weather is cold

A lot depends on the boat. We have a GRP cruiser and it stays lovely and warm during the winter and doesn't suffer with condensation.

 

All boats are different and it depends on the quality of the build. I personally wouldn't buy a boat constructed from both steel and GRP. The join between the two is always going to be a weak spot as the two materials will react differently to changes in temperature and humidity.

[muddywaters]

A lot depends on the boat. We have a GRP cruiser and it stays lovely and warm during the winter and doesn't suffer with condensation.

 

All boats are different and it depends on the quality of the build. I personally wouldn't buy a boat constructed from both steel and GRP. The join between the two is always going to be a weak spot as the two materials will react differently to changes in temperature and humidity.

This was partly why I ask the question, because I suspected it might be the case.

My main preference would be all steel but have seen one or two of these mixed boats, none of which have made my list of possible boats to look at

[carlt]

Having lived on a boat with a steel hull and GRP/wooden cabin I'd say that if you are having problems with leaks then you are not maintaining your boat properly.

 

If the gap between the two materials is bridged by the correct sealant then different coefficients of thermal expansion is no more of a problem than a steel cabin with correctly sealed aluminium, plastic or wooden windows.

Edited July 6, 2014 by carlt

[Naughty Cal]

The trouble is when buying a used boat you are buying someone else's to do list. The older the boat in all likely hood the longer the to do list!

[Keeping Up]

It depends very much on the construction.

 

A lot of Harborough boats (like the one we had) used a sandwich of two thin sheets of GRP glued outside a layer of expanded foam. This was extremely warm and never had any condensation issues (particularly as on ours there was T&G facing inside with a layer of additional insulation) but others had just a single skin of GRP which was likely to be very cold.

 

Certainly we were plagued by leaks between the roof and the hull, but it was perfectly suitable for living on - even in the depths of winter.

[Paul H]

A lot of GRP topped narrow boats were built as a hire boats - for summer use only. I knew someone who lived aboard one of those slidey roof jobbies which IIRC were known as Frobisher Class. Little or no inulation, lots of condensation and used to wake up with his duvet frozen to the wall!

Paul

[Naughty Cal]

Did they not hire boats out during the winter in those days?

 

We have certainly had some bitterly cold days on hire boats (slidey roofed GRP broads boats) and with the heating on they have been great and nice and warm.

[Paul C]

Did they not hire boats out during the winter in those days?

 

We have certainly had some bitterly cold days on hire boats (slidey roofed GRP broads boats) and with the heating on they have been great and nice and warm.

 

They don't hire boats out in the winter nowadays! (In general). Yes, one or two boats might be out over winter but its the exception not the rule.

[Neil2]

I don't think the heat insulation issue is that relevant on a boat of this type, they can be just as warm as a steel boat. But these days a glass top boat would have to be in tip top condition to be worth looking at.

 

There are advantages - no rust being one, also a grp cabin boat is going to be extremely stable as the cabin weighs a fraction of an equivalent steel one. There are also two big disadvantages for a canal boat, you can't realistically walk on the roof, and you can't really have a centre line on the roof either.

 

GRP cabin boats hail from the days when narrowboat builders were well versed in building hulls, less so in fabricating steel cabins.

 

Personally I'd rather have a wooden top boat than a glass top.

[Pykebird]

I lived for a year on a Harborough with a wooden, rather than grp top and had no problems. It was during the winter when we actually had proper snow and it stayed on the roof for ages, so not much heat loss!

[Keeping Up]

You can't usually jump down on to the roof from a lock side, but you can usually walk on the roof OK, especially if it has a reasonable number of wooden framing pieces.

[Arthur Brown]

A PLAIN grp boat is probably as warm/cold as a plain steel boat, it's thin and the weather is 3mm away. However Steel boats are now better insulated so an old GRP top/boat could be colder, but with suitable insulating it could be at least as warm as an insulated steel boat.

 

Mixed material boats are usually older than all steel boats so you get the "to do list" that comes with age too.

[RickH]

The strength of a grp roof should not be an issue as long as it's built correctly . Grp sailboats have to withstand much greater pressures than a narrowboat ever will . Deck mounted masts also have great lateral pressure which grp sailboats handle well . The only issue is the join between the grp and steel which if badly fitted will seperate and allow water into the grp sandwich itself .

[Phil Ambrose]

A PLAIN grp boat is probably as warm/cold as a plain steel boat, it's thin and the weather is 3mm away. However Steel boats are now better insulated so an old GRP top/boat could be colder, but with suitable insulating it could be at least as warm as an insulated steel boat.

 

Mixed material boats are usually older than all steel boats so you get the "to do list" that comes with age too.

Hmm are you suggesting GRP boats are only 3mm thick? We lived on a 40ft x 12ft GRP cruiser for 10 years and I can assure you I could only just get through it with a hole saw, so at least 14mm/15mm thick.

Phil