Plastic boats

[Phil Ambrose]

11 hours ago, Naughty Cal said:

They do build their modern fleet.

Thanks for the info Rachael, 

Phil

[OldGoat]

16 hours ago, Dr Bob said:

If the glass fibre laminate has voids in it, or there is an air bubble that has not been released in the curing gel coat prior to lay up,  then that is a site where osmosis can occur. The gel coat/laminate is therefore the permeable membrane (all plastics/thermosets are permeable to some extent). The void will contain salts from the curing agents used in the GRP (ie the cobalt accelerators) and styrenic molecules plus water that will be present on the glass. This will be a concentrated aqueous based cocktail and therefore become the high concentration solution to which the fresh water will flow. Absolutely it is osmosis.

It shouldnt however be confused with degradation of laminates caused when water gets into the laminate via gel coat damage and wicks up the glass fibres

I've always wondered why boats in my area (Thames) are taken out of the water in the 'off' season - it's to avoid osmosis. Thank you, a mystery solved!

[zenataomm]

On ‎25‎/‎09‎/‎2017 at 09:07, carlt said:

2 winters on a Dawncraft 27 heated by a Taylor's paraffin heater.

 

 

Toasty warm and no condensation.

The boat is long gone but I still have the heater

Was that the Dawncraft that ended up in a field opposite the Wyken Basin entrance?

[Sunflower16]

All this talk of osmosis makes me nervous.......my recently purchased, rather ancient 47-50 year old FH Childs / Teal cruiser had a pre-purchase survey as I was rather concerned about the osmosis issue- survey added about 10% to its modest purchase price but would not have been able to get fully comp isurance without a survey.  Surveyor claimed no evidence of osmosis whatsoever and declared the hull totally sound........having just last week stripped out the floor(no inspection hatches as laminate (of all thngs) was laid down on a base of chipboard ( againof all things! ) and bow area due to deck fittings water ingress and muppetry bilge pump wiring (auto bilge left unconnected,plus pump lying loose flopping around the bilge, which was then permanently closed with screwed down decking....) Water had no way out and lay underfloor and in the bilge for around 2 years (which is when the sellers refitted it) .  Interior floor GRP seems very hard, no soft areas or squashy spots - I cleaned it and painted with bilge paint today before the new floor goes down. Can an ancient GRP boat from ths era be osmosis free?   

Edited September 30, 2017 by Sunflower16

[Dr Bob]

51 minutes ago, Sunflower16 said:

All this talk of osmosis makes me nervous.......my recently purchased, rather ancient 47-50 year old FH Childs / Teal cruiser had a pre-purchase survey as I was rather concerned about the osmosis issue- survey added about 10% to its modest purchase price but would not have been able to get fully comp isurance without a survey.  Surveyor claimed no evidence of osmosis whatsoever and declared the hull totally sound........having just last week stripped out the floor(no inspection hatches as laminate (of all thngs) was laid down on a base of chipboard ( againof all things! ) and bow area due to deck fittings water ingress and muppetry bilge pump wiring (auto bilge left unconnected,plus pump lying loose flopping around the bilge, which was then permanently closed with screwed down decking....) Water had no way out and lay underfloor and in the bilge for around 2 years (which is when the sellers refitted it) .  Interior floor GRP seems very hard, no soft areas or squashy spots - I cleaned it and painted with bilge paint today before the new floor goes down. Can an ancient GRP boat from ths era be osmosis free?   

That is the problem with a thread like this. Osmosis is blown up into something it is not.

Probably 90%+ of osmotic problems are purely cosmetic with the blisters forming just under the gel coat level, caused by small air bubbles swelling with water. They can reasonably easily be repaired and will never sink the boat as the damage is not structural. They will have appeared long before the boat gets to 40 years old. On less than 10% of the osmotic problems, the voids that are the sites of the blisters could be larger and MAY lead to some structural problems but not always. There are always horror stories but Osmosis is not the boat killer some people on here make out. Maybe a few percent of osmosis problems could kill a boat.

Now, your boat is nearly 50 years old so will be hand laid up with likely a thick laminate. Today GRP boats are made with laminate thicknesses almost a thrid of the thickness. It is very difficult to have structural problems with a thick laminate and especially if a surveyor has said it is fine. Yes they do miss stuff but in this case I would not worry. In 1978 I built a canadian canoe - open top. It sat in our garden for 40 years filling up with water whenever it rained. 40 years on, not an issue with laminate performance - and it was built with gash resin, gash glass but with lots of skill!!

You ask if it can be osmosis free. If it is not blistered now - yes. As I have said on multiple occasions in this thread, the biggest enemy is not osmosis but gel coat cracks that lets water wick up the fibres. Your surveyor should have spotted these and didnt, so likely not an issue. Even then, on your thick laminate, you are unlikely to have a problem. If you are in any doubt, go back and ask you surveyor about the structural integrity.

 

[carlt]

3 hours ago, zenataomm said:

Was that the Dawncraft that ended up in a field opposite the Wyken Basin entrance?

Yes...Stolen, dragged onto the field and stripped of everything.

The bottoms survived being dragged onto the bank though so I guess Osmosis wasn't a problem...

 

[Phil Ambrose]

18 hours ago, OldGoat said:

I've always wondered why boats in my area (Thames) are taken out of the water in the 'off' season - it's to avoid osmosis. Thank you, a mystery solved!

Osmosis is unlikely to be the reason boats are stored ashore, if that was the case The Broads would have a problem as there is not enough hard standing available fir a fraction of the boats afloat there.

Usually when GRP boats are lifted and stored ashore it enables work to be done on the hull, antifoul etc and to avoid issues with raw water cooling systems from freezing particularly the weed filters.

Phil

[Naughty Cal]

On 30/09/2017 at 22:24, Dr Bob said:

That is the problem with a thread like this. Osmosis is blown up into something it is not.

Probably 90%+ of osmotic problems are purely cosmetic with the blisters forming just under the gel coat level, caused by small air bubbles swelling with water. They can reasonably easily be repaired and will never sink the boat as the damage is not structural. They will have appeared long before the boat gets to 40 years old. On less than 10% of the osmotic problems, the voids that are the sites of the blisters could be larger and MAY lead to some structural problems but not always. There are always horror stories but Osmosis is not the boat killer some people on here make out. Maybe a few percent of osmosis problems could kill a boat.

Now, your boat is nearly 50 years old so will be hand laid up with likely a thick laminate. Today GRP boats are made with laminate thicknesses almost a thrid of the thickness. It is very difficult to have structural problems with a thick laminate and especially if a surveyor has said it is fine. Yes they do miss stuff but in this case I would not worry. In 1978 I built a canadian canoe - open top. It sat in our garden for 40 years filling up with water whenever it rained. 40 years on, not an issue with laminate performance - and it was built with gash resin, gash glass but with lots of skill!!

You ask if it can be osmosis free. If it is not blistered now - yes. As I have said on multiple occasions in this thread, the biggest enemy is not osmosis but gel coat cracks that lets water wick up the fibres. Your surveyor should have spotted these and didnt, so likely not an issue. Even then, on your thick laminate, you are unlikely to have a problem. If you are in any doubt, go back and ask you surveyor about the structural integrity.

 

Construction methods moved on over time. Our more modern hull for example uses the inner liners for strength which means that the outer hull can be much thinner and lighter weight. If it was heavily laid up like older boats it would be too heavy and need a much bigger engine.

We were lucky enough to go and see the Sealine factory before they were taken over by Hanse to see how the boats were made. They were still hand laid up at that point. It was very much an eye opener as to how much time and work goes into making each boat.

[Dr Bob]

14 hours ago, Naughty Cal said:

Construction methods moved on over time. Our more modern hull for example uses the inner liners for strength which means that the outer hull can be much thinner and lighter weight. If it was heavily laid up like older boats it would be too heavy and need a much bigger engine.

We were lucky enough to go and see the Sealine factory before they were taken over by Hanse to see how the boats were made. They were still hand laid up at that point. It was very much an eye opener as to how much time and work goes into making each boat.

Fully agree, a lot different these days....but not all good. We bought our lumpy boat  in 2005 (at large expense) and as it looked so good, a friend ordered one. His unfortunately suffered some huge problems as the inner liner was not bonded properly to the external hull ending up with the keel flexing too much and causing cracks around the keel area. Big cost to sort out. Really glad narrow boats dont have keels. (....and it want a Bavaria or a Hanse!!!!!). Our 2005 boat was fine.

[Naughty Cal]

10 hours ago, Dr Bob said:

Fully agree, a lot different these days....but not all good. We bought our lumpy boat  in 2005 (at large expense) and as it looked so good, a friend ordered one. His unfortunately suffered some huge problems as the inner liner was not bonded properly to the external hull ending up with the keel flexing too much and causing cracks around the keel area. Big cost to sort out. Really glad narrow boats dont have keels. (....and it want a Bavaria or a Hanse!!!!!). Our 2005 boat was fine.

Yes there is a huge difference in build quality between boats of the same design by the same builder. But if you see how they are made then you can fully understand how that can and does happen.

Not that that makes it any easier when you are on the receiving end of a less then perfect hull and you need to get it sorted out of course.

[Murflynn]

I don't like double-skin hulls.

When I bought my little Bonwitco I had a choice of (1) an early single skin boat made with a heavy lay-up to which was added a GRP-sheathed plywood floor above the foam buoyancy, or (2) a more modern double skin boat with a sandwich of foam between the skins.  Luckily I opted for the single skin.  I found that foam buoyancy was saturated with water.  I removed the floor and the foam; I estimated it had soaked up 200litres of water.  The GRP was as sound as a pound.  If the double-skin version had soaked up some water the hull would have lost its integrity altogether.  

[Naughty Cal]

On 03/10/2017 at 09:04, Murflynn said:

I don't like double-skin hulls.

When I bought my little Bonwitco I had a choice of (1) an early single skin boat made with a heavy lay-up to which was added a GRP-sheathed plywood floor above the foam buoyancy, or (2) a more modern double skin boat with a sandwich of foam between the skins.  Luckily I opted for the single skin.  I found that foam buoyancy was saturated with water.  I removed the floor and the foam; I estimated it had soaked up 200litres of water.  The GRP was as sound as a pound.  If the double-skin version had soaked up some water the hull would have lost its integrity altogether.  

Ours is slightly different to the foam sandwich type construction. The inner lining trays and fixtures are bonded to the outer skin in various places to form the hull integrity . No foam layer.

[peterboat]

The bathtub has a large keel and to semi keels at the edge of the hull, plus the ribs are all heavily bonded in and covered in fibreglass to stop water ingress of the plywood. The floor is very very solid and all well laid up, time will tell how long it lasts but I suppose at some point the hull will deteriate?

[mrsmelly]

On 9/25/2017 at 18:06, ditchcrawler said:

Dont try telling Mrsmelly that

 Yeah I just read that and thought how shit my Dickenson was. We had a Taylors on a Teak boat we owned though and that was a great bit of kit.

[Naughty Cal]

44 minutes ago, peterboat said:

The bathtub has a large keel and to semi keels at the edge of the hull, plus the ribs are all heavily bonded in and covered in fibreglass to stop water ingress of the plywood. The floor is very very solid and all well laid up, time will tell how long it lasts but I suppose at some point the hull will deteriate?

Just the centre keel on the boats we are looking at.

A picture of the hull on this surveyors website who interestingly comments on osmosis briefly.

http://www.europeanmarinesurveys.com/2015/01/alpha-craft-32-pre-purchase-survey-review/

[peterboat]

1 hour ago, Naughty Cal said:

Just the centre keel on the boats we are looking at.

A picture of the hull on this surveyors website who interestingly comments on osmosis briefly.

http://www.europeanmarinesurveys.com/2015/01/alpha-craft-32-pre-purchase-survey-review/

If you look at the picture out of water you can see on each edge of the hull little strengthening keels, on the inside of the hull is four lifters bonded in above these little keels when they lifted the hull out of the mould. As yet all the floor bearers have been in perfik condition and we are now by the front door, the boat has been flooded at some point but this does not matter to me as all the interior is now out.

Edited October 5, 2017 by peterboat

[Naughty Cal]

1 hour ago, peterboat said:

If you look at the picture out of water you can see on each edge of the hull little strengthening keels, on the inside of the hull is four lifters bonded in above these little keels when they lifted the hull out of the mould. As yet all the floor bearers have been in perfik condition and we are now by the front door, the boat has been flooded at some point but this does not matter to me as all the interior is now out.

Found a better image. Had not noticed the smaller keels before!

Explains why they go in such a straight line when underway and are a pig to turn around. 

[Richard T]

To return to topic on the Soar there are two fibreglass narrowboats made by a firm called Fibreline of Mansfield - I suspect that they went out of business many years ago. They are both used as liveaboards. One is about 35ft and the other 45ft. The latter appears to have been made in two sections with stainless steel joining plates. I did take photos but can't track them down.

I have found photos in this thread

https://canalworld.net/forums/index.php?/topic/54095-fibreglass-narrowboat/&tab=comments#comment-1021407

Edited October 5, 2017 by Richard T
further information added