Repairing / Replacing the FOAM thas between outer and inner PVC skins

[Capt Popeye]

Repairing /Replacing the INNER foam core ; is this possible at all ; My boat has been declared Non Repairable by a Fella because the Inner Foam Core he says , is soft and faulty (irrepairable?) Is this so ? Is it possible to make holes in the Inner PVC skin and inject suitable foam into the cavity between the outer and inner skins ?

The Boat is advertised as Unsinkable because this Inner Foam will give boat sufficient Boyancy by excluding Water from accessing tween the hulls ?

From my observations , many Boats do not have an Inner Core of Foam , they rely upon the Outer Skin being water tight , ie no holes in it ; plus a Bilge pump or two for the Spray and any other water coming over the sides ?
Thanks CP

 

[Poignard]

Is this any help? -

https://www.westsystem.com/app/uploads/2022/10/Fiberglass-Manual-2015.pdf

Page 29 Section 5.2

 

[AntarcticPilot]

Without giving a lot more detail, you won't get many answers. What make and model is the boat? If it's genuinely PVC, that suggests it's a dinghy, and PVC dinghies are generally regarded as difficult to repair even without a foam core; repairs are generally short-term patches. Foam cores just make it harder, and without knowing what kind of foam was originally used it is impossible to suggest a course of action.

PVC dinghies that have split are generally regarded as end-of-life.

 

[Concerto]

Foam core can be used in decks and top sides of yachts. It is much better than balsa core as it does not rot if it gets wet. PVC will certainly be unlikely to be repairable.

 

[PCUK]

If the foam is gone but the outer skin is intact then the boat is still usable. The foam only keeps it afloat if the hull is totally flooded. Depending on the size you can fit buoyancy bags to do the same job as the foam.

 

[Capt Popeye]

Hi boat is a SEAPRO 700 its an Outboard Runabout 14ft loa I understand that its a PVC build material , just one patch it appears that the PVC hull decking if 'flaking' but not an open hole , just I guess restricting its strength ; To my investigations , the inner and outer Hull is not holed at all , we were out at weend for about 2 hours with a 25hp Ob propelling it , no water was found or observed entering the hull at all ;It was quite dry when trailerd out ;
My take is that the Foam between the hulls is to prevent water entering there , so providing the Boat with a positive boyancy , if IF water entered the cavity ; as the Foam would not allow that as no room there ?

As a poster states PCUK (I think) boyancy bags etc would offer unsinkability in a similar way to the Foam inserted between the decking ?

My research indicates that Epoxy Putty should be suitable for PVC repairs to Damage and Holes , any thoughts ?

Thank you for all replies much appreciated ; CP there is an online Fella claiming that my boat is a Write Off so practically worthless

 

[Capt Popeye]

Is this any help? -

https://www.westsystem.com/app/uploads/2022/10/Fiberglass-Manual-2015.pdf

Page 29 Section 5.2

Thank you its very helpfull , appreciated

 

[oldbloke]

Hi Capenhurst, could you go back a couple of steps and explain what problem you have that you are trying to solve?

 

[AntarcticPilot]

Hi boat is a SEAPRO 700 its an Outboard Runabout 14ft loa I understand that its a PVC build material , just one patch it appears that the PVC hull decking if 'flaking' but not an open hole , just I guess restricting its strength ; To my investigations , the inner and outer Hull is not holed at all , we were out at weend for about 2 hours with a 25hp Ob propelling it , no water was found or observed entering the hull at all ;It was quite dry when trailerd out ;
My take is that the Foam between the hulls is to prevent water entering there , so providing the Boat with a positive boyancy , if IF water entered the cavity ; as the Foam would not allow that as no room there ?

As a poster states PCUK (I think) boyancy bags etc would offer unsinkability in a similar way to the Foam inserted between the decking ?

My research indicates that Epoxy Putty should be suitable for PVC repairs to Damage and Holes , any thoughts ?

Thank you for all replies much appreciated ; CP there is an online Fella claiming that my boat is a Write Off so practically worthless

The problem with most forms of filler or putty is that PVC has vastly different elasticity and chemical properties from GRP. The former means that most types of filler designed for GRP will eventually flake off as they flex differently to the PVC substrate and the latter means that the adhesion is not good. That's why people advocate using welding techniques, so the new material is the same as the old. PVC is a thermoplastic, so welding works - it doesn't on GRP which undergoes a chemical change as it hardens. But obtaining a good cosmetic finish is another matter.

The foam may be adding structural rigidity; as @Concerto says, foam or balsa is commonly used to produce a light, stiff structure for the decks of boats (nothing to do with flotation - it's purely a strength thing). The principle is that the inner and outer skin bear most of the tensile and compressive forces, but to be effective they must be kept apart, which is the role of foam or balsa. The foam may be a critical part of the engineering of the bottom of the boat,

 

[Capt Popeye]

Hi Capenhurst, could you go back a couple of steps and explain what problem you have that you are trying to solve?

Hi oldbloke ; I have anOutboard Motor Boat made (I understand) from PVC (its about 12 years old) the narrow side decking (only place where one can walk fore n aft ) has started towhat I would call , de laminate , its NOT a through deck hole but an area about large as palm of hand , thats flaking so looks bad , but no hole apparent ; A fella on Facebook where boat is advertised has commentated twice that it shows the inner core , material is deteriorated so hull needs full inner core replacing ; I have approached a local GRP repairs fella , he says that GRP cannot be used straight onto PVC , but he can get suitable other materials to repair the PVC damage but at about 1300 which is difficult to agree to as it is lotsa money considering its worth ? maybe ?? It has me worried but I see that there can be a solution to the aledgedly de graded PVC .
I am looking at wether an acceptable looking and functioning repair can be made , from other materials ; Epoxy Putty has been mentioned , to repair the PVC skin but can the inner Foam (??) be replaced , or indeed , does it need to be replaced ?

If the inner and outer skins are intact (as far as one can see) surely its just like most boats , made of GRP which might only have one skin , the outer one , boyancy being obtained by flotation bags /devices ; In my understanding , if the inner and outer skins are intact flotation devices should work on keeping her afloat if water comes on board ?

Maybe the Fella offering his opinions does no know as much as he believes he does ?

 

[oldbloke]

I am sure that the condition of the foam in 99% of the boat is irrelevant. It may be, however, that the foam in the damaged area is failing because of related trauma and is no longer supporting the deck, hence the fatigue of the deck material. If so , finding a material to repair the deck is not really the issue, you will need tofind a way of supporting the deck. Such as; injecting some kind of resin/foam/goo. Or getting to the underneath surface and attaching a supporting plate, or just screwing/glueing a plate on top.
I see that Seapro are still in business, have you spoken to them

 

[Capt Popeye]

I am sure that the condition of the foam in 99% of the boat is irrelevant. It may be, however, that the foam in the damaged area is failing because of related trauma and is no longer supporting the deck, hence the fatigue of the deck material. If so , finding a material to repair the deck is not really the issue, you will need tofind a way of supporting the deck. Such as; injecting some kind of resin/foam/goo. Or getting to the underneath surface and attaching a supporting plate, or just screwing/glueing a plate on top.
I see that Seapro are still in business, have you spoken to them

Hi there THANK you ; no thought they were not in business any longer , so will look them up now; Thank you ; I had thought of attatching Deck Anti Slip Plates to a repaired top surface of the damaged Side Decks , which I thought having repaired the Broken Surface with something , the Anti Slip Decking plates would provide better foot grip , as its a tad slippy now , plus the actual repairs would not necessary have to be Mirror Sharp Surfaces as they would be covered over : Thanks gota complete my thoughts plus research , great outcome CP

 

[PCUK]

In my experience, everything is repairable and this should be pretty easy now we've discussed it in detail. Some pic's as soon as you are able would be most appreciated.

 

[Capt Popeye]

In my experience, everything is repairable and this should be pretty easy now we've discussed it in detail. Some pic's as soon as you are able would be most appreciated.

Hi PCUK yep off to take Boat photos soon , then post them on here ; Many thanks CP

 

[Capt Popeye]

Hi PCUK yep off to take Boat photos soon , then post them on here ;

Well that took far longer than planned , at last is a Photo of the damaged are on the Boat made from PVC , its really a Crack which has been tampered with , so its now more like a Hole , thats a Crack shape , showing what looks like the Internal Foam Core underneath , that feels quite hard to me ; its certainly shows no sign of absorbing water or is damp at all , so recon its still dry foam ;



Thanks for all the help etc CP

 

[Metalicmike]

I would seek a second opinion. The hull is probably polyethylene and produced in two halves and bonded together. The hull is then injected with expanding foam. If this is the case, making an invisible repair Is bordering on impossible as polyethylene is difficult to adhere to. I would consider making it good and then laying decking material or marine ply along that part of the deck. Do both sides so that it looks original. Hope it goes well for you.

 

[Capt Popeye]

I would seek a second opinion. The hull is probably polyethylene and produced in two halves and bonded together. The hull is then injected with expanding foam. If this is the case, making an invisible repair Is bordering on impossible as polyethylene is difficult to adhere to. I would consider making it good and then laying decking material or marine ply along that part of the deck. Do both sides so that it looks original. Hope it goes well for you.

Hi well thank you for your suggestion , in some ways I am tinking of similar method of repairs to yours ; The decking is only on the Port side of my boat , so access inside boat is restricted to that one side : this might make it easier to make a repair , as I will not have to marry up both sides , just concentrate on the One side : Yes I was looking at imitation Decking based I think on using Ply or a Plastic with built in imitation Boards ; So making good as best can the Original damaged decking , not worrying about getting a really smooth finish then covering a length of the Damaged decking with the imitation PLy / Plastic /GRP ? which should give me a far stronger Deck than the oroginal did or would have done : does that sound like a plan ? thanks CP
I have ordered a tin of Plastic Filler from Toolstation which might work well ? but I could try it out on something else ? firstb

 

[Metalicmike]

Hi well thank you for your suggestion , in some ways I am tinking of similar method of repairs to yours ; The decking is only on the Port side of my boat , so access inside boat is restricted to that one side : this might make it easier to make a repair , as I will not have to marry up both sides , just concentrate on the One side : Yes I was looking at imitation Decking based I think on using Ply or a Plastic with built in imitation Boards ; So making good as best can the Original damaged decking , not worrying about getting a really smooth finish then covering a length of the Damaged decking with the imitation PLy / Plastic /GRP ? which should give me a far stronger Deck than the oroginal did or would have done : does that sound like a plan ? thanks CP
I have ordered a tin of Plastic Filler from Toolstation which might work well ? but I could try it out on something else ? firstb

The main issue is waterproofing. I had a problem with my windows as the first fix failed with the heat and succumbed to gravity, after a lot of research I settled on Bostik Simson ISR 70-08 AP and am very pleased with the results.

 

[oldbloke]

If you are really confident that it actually is pvc then I would use either a specialist glue or epoxy? I dont think a polyester car body type filler will stick well enough. There are some really sticky glues out there nowadays

 

[Capt Popeye]

If you are really confident that it actually is pvc then I would use either a specialist glue or epoxy? I dont think a polyester car body type filler will stick well enough. There are some really sticky glues out there nowadays

Hi well I am advised by our Loca GRP fella that its NOT GRP but a plastic , so he cannot use a GRP on it at all , will melt it ;So thinking of asking a local Window Frame repairer if they can identify the Material used in the Boat making