JWS Marine services is one of the leading osmosis repair centres on the South coast with a 3000sq foot undercover workshop at Southsea Marina. This enables us to reduce the cost for the customer and we also offer discount on marina cost related to the job.


Osmosis Prevention

Osmosis prevention should start when you buy a new boat.Up to 3 coats of epoxy coating can be added to a new hull and for best protection this should be done before the hull is out in the water. This will give a good start to the life of the boat. More and more new boats are now launching without this protective layer. For a professional protective fisnish the follwoing work should be undertaken:

1. Blast Hull

2. Blast Keel

3. Sand Hull

4. Spot fill hull

5. Corro-tech epoxy keel with 5 coats

6. Fill keel with 2 fills of epoxy filler

7. Sand keel

8. Apply new keel joint

9. Paint hull with 3 coats of epoxy primer prevention

10. Antifoul hull with 2 coats


Full Osmosis Treatments

Osmosis prevention for older boats is more complex. JWS Marine Services ensure that boats stand for a least 2 weeks as this allows the hull to dry out so when the moisture reading are taken from the hull the are more accurate. Accurate and regular readings are important to ensure the epoxy is not applied to a wet hull. Epoxy paint is a waterproof membrane that keeps moisture out but will keep moisture in too. Moisture entrapment can accelerate the osmosis process by up to 50%. If you need advice on osmosis prevention or treatment - just ask the experts at JWS.


Almost all glass fibre boats, whch are not protected, will develop some degree of osmotic symptoms at some point in their lives. JWS Marine Services is an approved International osmosis treatment centre and is able to treat any problems you might find. We are experienced in using a variety of products such as Blakes SFE 200, International Gel shield Plus, AMC ME100 epoxy coating to provide the best solution for each in individule problem. Once a boat has osmosis the full treatment consists of the total removal of gel coat. This is done by gel peeling this is done so the hull can dry out. We then use a specialist blasting company who sand balst the hull to expose the fibreglass blisters and any further blisters that have been missed by the peeling process. Washing the hull will increase the drying time by up to 50% than natural drying so at JWS we dont stop washing until the time comes to put the boat in the shed. 


JWS Marine Services uses the HotVac system to treat osmosis which consists of 4 large pads that are placed onto the hull, through which a controlled heat and vacuum is applied. This removes and absorbs water from the affected hull along with compounds which cause corrosion, weakening of the glass and resin bonds, delamination and blistering. At this point we can instructed a surveyor to monitur the application of the product that is chosen for the rest of the treatment. The treatment comprises of one layer of epoxy, 2 filling layers of under water filling epoxy, sand hull, 5 layers of epoxy then 2 coats of primer and 2 coats of antifoul then launch. As you can see we don't just put 4 layers on with JWS you get 6 layers of epoxy for the same cost as four, this give your boat abetter finish and in all the years JWS have poxied hulls, we have not had one come back or complaint.

The process of our Osmosis Treatment is as follows - Osmosis Treatment Video

1. Hull - Gel peel                      2. Hull & Keel(S) blast              3. Apply Corro-tech to keel(S) and fill

Peelsmall                 Blastsmall                    Keelssmall

4. Hot Wash hull                      5. Tent hull & HotVac                6. Sand hull & 1 AMC epoxy coat 

   Hot wash Video                                         07. small                   1AMCcoat


7. We fill and fair the hull between each coat

8. Remaining 5 coats of AMC epoxy.

09       10       COMPsm


As you can see from the last picture we finshied the treatment with a Copper Coat application.

There are some optional extras avalible with the Osmosis treatment -

Option 1: Extra Layer(S) of 292 tapered cloth

Option2: Surveyors oversight, this consist of 3 visits 1) Moisture readings following initial peel.

                                                                            2) Moisture reading prior to applcation.

                                                                            3) Final inspection and written report

We have a number of surveyors we use for this service but if you have a preferance we are happy to use your preferance.



More pictures of Osmosis treatment we have carried out can be found in our gallery in Osmosis Repair section.

Latest Jobs

Below you can view some of our work, from start to finish

  1. Show All
  2. Osmosis
  3. Copper Coat
  4. Woodwork
  5. Blasting
  6. Maintenance
  7. Gel/GRP Repairs
  8. Re-fit
  9. Insurance Works
  10. Twister 28 - New Cabin Top
  11. Sun Odyssey 47 - Rudder Fabrication
  12. Keel seams and Keel Bolts
  13. Re-fit of Growler - Fairey Spearfish Power Cruiser
  14. New and Refurbishment of teak decks
  15. Bow Thruster Installations
  16. Spray Applications
  17. Laurent Giles Wooden Classic project
  18. Copper Coat - 27ft Motor Boat
  19. Copper Coat - Wessex 390
  20. Sigma 41
  21. Re-spray RM890
  22. Dehler 41 - Spray hull


Mr Brighouse, Chichester

I chose to use JWS for my anti-fouling, wood repair (interior and exterior) and tiller work to be carried out. I was not disappointed with their thorough service and professionalism before, during and after work. Highly recommend them and would use again.

Click here to read all of our testimonials.


JWS Marine Services pride our self's on our ability to give the customer what he or she wants. We offer a range of services in order to restore your vessel and take great care in doing so. Click one of the below to find out more.

Copper Coat

When we apply copper coat we do it under cover in our 2000sq footwork shop. This will allow us to monitor the application of the copper coat and keep the hull completely clean at all times.

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Osmosis prevention should start when you buy a new boat. Up to 3 coats of epoxy coating can be added to the new hull and for best protection this should be done before the hull is put in the water.

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Shipwright & Wood

JWS Marine services real passion is wooden classics and we enjoy nothing more than working with them whether it be from a minor repair to a total re-fit and all that is in between.

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GRP Repairs

Whether it be from a small scratch or some star crazing to a hole or dent caused by an impact, with our expertise and high quality finish on all gel repairs carried out you will be pleased with the finished result.

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When it comes to your boat, keeping her looking tip top is always first on the list, with our maintenance programs we are able to provide a detailed program tailored to you and your boat need, whether that be a basic yearly Antifoul to a full maintenance program

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Our new blast machine is designed for soda blasting but works well with more abrasive media, so we are able to offer a variety of blasting options all with great results. Furthermore we are mobile so we are not limited to Southsea Marina.

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Gas Works

Gas safety checks with certificates available, arried out and supplied by a registered Gas Safe engineer. Please give us a call to discuss all your gas safety requirements and installations, alternativley pop us an email and we will call you back to arrange a visit.

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Insurance Works

We are happy to provide competitive quotes for all insurance claims/works please contact us with all your details.



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About JWS Marine services Ltd


JWS Marine Services has earned an excellent reputation for performing boat fibreglass repair and fabrication. The key to quality marine fibreglass work is preparation and quality materials. With over 22 years of marine fibreglass experience, we produce consistent high quality work. At JWS Marine Services we are constantly working with manufacturer reps to stay abreast of the newest marine fibreglass products and processes. The combination of high technology materials, extensive preparation and years of experience results in high quality & competitively priced services for our customers.

JWS Marine offer an extensive boat detailing program, it be just a wash down or a complete buff and polish. We can customise a program for your boat all year round keeping it looking new and protecting the paint work and gel coat from the harsh elements, so all you have to do is jump on board and enjoy your boat. For all boat repairs Portsmouth, please contact JWS Marine.


If you would like some more information on our services, would like to discuss your needs or simply would like a quote, please fill in our form or ring the number below.

The Boatshed, Southsea Marina,
Fort Cumberland Road,
Southsea, Portsmouth,
Hampshire, PO4 9RJ
02392 755 155 or 07803 616229  This email address is being protected from spambots. You need JavaScript enabled to view it. or This email address is being protected from spambots. You need JavaScript enabled to view it.

Company Reg No: 05180060                  Company VAT No: 838 6772 75