Osmosis avoidance, detection, treatment
Osmosis-Is a problem with fibreglass hulls built from polyester resin... The problem is that water is, able to make its way through the gel coat and in to the fibreglass laminate. Gel coat is not completely waterproof, water penetration does occur. If the water is able to find its way into any air bubbles or small voids that have been left behind from the laminating process it will mix with chemical residue (styrene, MEKP, etc) to form a dense acidic liquid. Because that liquid is more dense than the seawater on the outside of the hull water is drawn from the outside into the void in an effort to equalise the pressure difference, the result is that the void pressurises and forces the outside layer into a blister which shows on the outside of the hull often when the hull is removed from the water a dark liquid can be seen forcing its way back out through the laminate, or gel coat. The blister is actually a small delaminated section of hull, sometimes just under the gel coat but often into the outside layers of CSM depending on the lay up. The process of water penetration is called osmosis and is the same process used in nature by plants to transmit water from roots to leaves.
Avoidance-FRP boats these days are not as prone to osmosis as they were some years ago. Boat builders have realised that they put their product and company name in jeopardy by using cheaper materials and taking shortcuts in production. Hulls that don’t have osmosis problems have a sealed laminate, they use vinyl ester, or isothalic polyester resin rather than orthothalic Quality control the temperature, the humidity, and take good care to lay up using proven techniques. The underwater surface should be sealed with a good thickness of epoxy paint prior to antifouling
Detection- Is not always straight forward, the best way is to view the bottom of the boat when it is first hauled out, and by looking along the wet surface the raised blisters will show up and should be marked. Often as the hull dries the blisters quickly disappear. This is because the surface has been softened and the liquid is allowed to escape as the water is no longer pressuring on the outside of the hull. This will happen quite quickly as the hull dries and often only one hour after haul out the blisters have disappeared. The problem is still there it’s just difficult to individually locate them. Sound tapping with a hammer will find the blisters as they are just small delaminated areas. Often so small that it’s difficult to cover the entire surface with a hammer and feel confident all the blisters have been located. Antifouling should be removed to be sure of finding the full extent of an osmosis problem.
Repair-There are only two proven methods of repair. The first is to remove the affected area of each blister individually, dry out and epoxy fill which is considered as damage control rather than repair. Or the second method is to plane the surface of the hull down to a level where the laminate is healthy (sometimes that is not possible), dry out and re laminate with a resin rich matrix back to original thickness. This is often done with vinyl ester resin and sealed on the outside with a good thickness of epoxy paint.
Monday, February 28, 2011
Thursday, February 24, 2011
Case Studies
Case study (covers 5 learning outcomes)
These case studies are to be your Portfolio. They will show that you understand the learning outcomes and you know how to apply them in a practical way
Identify the learning outcome that applies to each case study
Put yourself in the position of managing a boatbuilding maintenance and repair yard when considering the following scenario’s
In your position as manager you need to be able to advise your client on a method of repair from initial survey to job completion. Use sketches as appropriate
Most boat owners are very careful about who they get to repair their ‘pride and joy,’ how much it is going to cost and wether they consider the method of repair is value for money. It is usually the manager’s job to assure them that your yard is the one they should choose to complete the repair
Case 1 (Osmosis Repair)
The Client owns a 12 metre power boat which is a “production built planing hull”. He has been grinding out osmosis blisters individually in the past during each annual haul out, however he thinks that the hull may now need a complete osmosis repair
On hauling out the boat you discover that the hull has many blisters and a complete osmosis repair is required
Describe how you would haul out using the Travel-lift
Describe for the owner your repair method including the method of survey
Case 2 (teak deck repair) (survey)
You have hauled out a yacht, which is built in timber using a cold moulded method; she has a plywood deck over laminated deck beams with teak laid over the plywood, this appears to be in good condition. While replacing deck cabin lights on the underside of the deck you discover extensive areas of soft plywood.
You need to establish what the problem is (survey)
After explaining your survey method describe fully how you could repair the problem
You require knowledge of the typical construction method of a “teak over plywood deck”. It is important to establish the cause of the problem so that it won’t happen again
Case study 3
On the same vessel the owner has complained of leaking windows and wants you to re-seal them. They are glass windows in an anodised aluminium frame. There are two main windows on each side and two smaller windows it is simply a matter of removing the windows and resealing them
Describe the process from start to finish step by step.
Specify the materials used
Case study 4
A 15 metre yacht has been holed above the waterline just behind the main chain plates; there is just the one hole with a small amount of surrounding damage.
The hole size is 900mm long starting from just aft of the chain plate and running aft it is 300mm wide in the middle of the topside
You first need to haul the boat in the travel-lift and place it in a cradle, and then move it inside your factory without the aid of the travel-lift, describe this complete process
The hull is composite, the lay up is as follows inner laminate total thickness is 2.5 mm the core is 12mm and the outside laminate total thickness is 3mm
Describe the repair process step by step including re-surfacing and preparing for re-launching
Case study 5
A client has asked you to Ground the underwater metal fittings on his 15 metre power boat.
Describe what he means
She is a wooden carvel planked hull and he has been having problems with galvanic corrosion
Describe what you would do, what concerns you would have, where you would place the zinc anodes, how you would connect to them
Case Study 6
A Stewart 34 has been booked in to your yard for antifouling, and to have the topsides and coamings polished.
She is one of the more recent polyester production laminate boats and when you have a close look you can see that the Gelcoat is in poor condition. There are a number of dings on the hull where the Gelcoat has been knocked and is damaged to the extent water might penetrate. The deck surface has also had a rough time, having had winch handles and other heavy items dropped on it while the boat has been racing.
You decide that you would be better to advise the owner to paint the hull, decks, and cabin top.
You need to justify your opinion that it will be better value for money to paint the exterior of the boat, even though the cost will be considerably more than just antifouling the bottom and polishing the Gelcoat.
Describe the complete painting process specifying the product you will use
Case study 7
You have to make a decision on the best way to get a 10 metre powerboat to a ship to be delivered to a new owner in Australia.
The options are to truck it to the port and have it loaded from the truck to the ship, or you take the boat by its own power to the ship and have it lifted from the water to the deck of the ship by crane.
Dimensions of the boat as follows:
Length 10m, Beam 3m, displacement 4500 Kilo, height of the hull and cabin top excluding ariels and a cradle 3m
The owner has suggested his preference would be to ship his boat in a container
Analyse the options and describe your analyses
The boat is stored at the Oram’s dry stack, describe how the boat is launched or put on a truck.
http://www.yachtsurvey.com/maitenance.htm
/marinesurvey.com/surveyguide/blisterblues.htm
These case studies are to be your Portfolio. They will show that you understand the learning outcomes and you know how to apply them in a practical way
Identify the learning outcome that applies to each case study
Put yourself in the position of managing a boatbuilding maintenance and repair yard when considering the following scenario’s
In your position as manager you need to be able to advise your client on a method of repair from initial survey to job completion. Use sketches as appropriate
Most boat owners are very careful about who they get to repair their ‘pride and joy,’ how much it is going to cost and wether they consider the method of repair is value for money. It is usually the manager’s job to assure them that your yard is the one they should choose to complete the repair
Case 1 (Osmosis Repair)
The Client owns a 12 metre power boat which is a “production built planing hull”. He has been grinding out osmosis blisters individually in the past during each annual haul out, however he thinks that the hull may now need a complete osmosis repair
On hauling out the boat you discover that the hull has many blisters and a complete osmosis repair is required
Describe how you would haul out using the Travel-lift
Describe for the owner your repair method including the method of survey
Case 2 (teak deck repair) (survey)
You have hauled out a yacht, which is built in timber using a cold moulded method; she has a plywood deck over laminated deck beams with teak laid over the plywood, this appears to be in good condition. While replacing deck cabin lights on the underside of the deck you discover extensive areas of soft plywood.
You need to establish what the problem is (survey)
After explaining your survey method describe fully how you could repair the problem
You require knowledge of the typical construction method of a “teak over plywood deck”. It is important to establish the cause of the problem so that it won’t happen again
Case study 3
On the same vessel the owner has complained of leaking windows and wants you to re-seal them. They are glass windows in an anodised aluminium frame. There are two main windows on each side and two smaller windows it is simply a matter of removing the windows and resealing them
Describe the process from start to finish step by step.
Specify the materials used
Case study 4
A 15 metre yacht has been holed above the waterline just behind the main chain plates; there is just the one hole with a small amount of surrounding damage.
The hole size is 900mm long starting from just aft of the chain plate and running aft it is 300mm wide in the middle of the topside
You first need to haul the boat in the travel-lift and place it in a cradle, and then move it inside your factory without the aid of the travel-lift, describe this complete process
The hull is composite, the lay up is as follows inner laminate total thickness is 2.5 mm the core is 12mm and the outside laminate total thickness is 3mm
Describe the repair process step by step including re-surfacing and preparing for re-launching
Case study 5
A client has asked you to Ground the underwater metal fittings on his 15 metre power boat.
Describe what he means
She is a wooden carvel planked hull and he has been having problems with galvanic corrosion
Describe what you would do, what concerns you would have, where you would place the zinc anodes, how you would connect to them
Case Study 6
A Stewart 34 has been booked in to your yard for antifouling, and to have the topsides and coamings polished.
She is one of the more recent polyester production laminate boats and when you have a close look you can see that the Gelcoat is in poor condition. There are a number of dings on the hull where the Gelcoat has been knocked and is damaged to the extent water might penetrate. The deck surface has also had a rough time, having had winch handles and other heavy items dropped on it while the boat has been racing.
You decide that you would be better to advise the owner to paint the hull, decks, and cabin top.
You need to justify your opinion that it will be better value for money to paint the exterior of the boat, even though the cost will be considerably more than just antifouling the bottom and polishing the Gelcoat.
Describe the complete painting process specifying the product you will use
Case study 7
You have to make a decision on the best way to get a 10 metre powerboat to a ship to be delivered to a new owner in Australia.
The options are to truck it to the port and have it loaded from the truck to the ship, or you take the boat by its own power to the ship and have it lifted from the water to the deck of the ship by crane.
Dimensions of the boat as follows:
Length 10m, Beam 3m, displacement 4500 Kilo, height of the hull and cabin top excluding ariels and a cradle 3m
The owner has suggested his preference would be to ship his boat in a container
Analyse the options and describe your analyses
The boat is stored at the Oram’s dry stack, describe how the boat is launched or put on a truck.
http://www.yachtsurvey.com/maitenance.htm
/marinesurvey.com/surveyguide/blisterblues.htm
Log Book of Learning
Repair and Transportation
Assessment 1
Logbook of learning
This assessment is worth 20% of your final grade
You are required to keep and present to the lecturer a log book of learning that reflects the learning process
Your log book should include examples of marine Repair Maintenance and Transportation which may include sketches with descriptions of the various possibilities.
The logbook will also cover problem solving and critical thinking
The outcomes to be covered by the learning log book are:
1. Assess the maintenance requirements of various vessels.
2. Determine the structural repair status of various vessels.
3. Derive appropriate structural repair requirements for various vessels.
4. Assess a wide range of vessels’ transportation requirements.
5. Investigate various vessels’ storage options.
Due date is 8th July 2011. Hand in to Student Central to be forwarded to
Lecturer Marine Technology Richard Wilson
Email rwilson@unitec.ac.nz
Work Phone 815 4321 ext.8700
Office Location building 107
Assessment 1
Logbook of learning
This assessment is worth 20% of your final grade
You are required to keep and present to the lecturer a log book of learning that reflects the learning process
Your log book should include examples of marine Repair Maintenance and Transportation which may include sketches with descriptions of the various possibilities.
The logbook will also cover problem solving and critical thinking
The outcomes to be covered by the learning log book are:
1. Assess the maintenance requirements of various vessels.
2. Determine the structural repair status of various vessels.
3. Derive appropriate structural repair requirements for various vessels.
4. Assess a wide range of vessels’ transportation requirements.
5. Investigate various vessels’ storage options.
Due date is 8th July 2011. Hand in to Student Central to be forwarded to
Lecturer Marine Technology Richard Wilson
Email rwilson@unitec.ac.nz
Work Phone 815 4321 ext.8700
Office Location building 107
Tuesday, February 22, 2011
portfolio of evidence
testing
Repair and Transportation
Portfolio of evidence
This assessment is worth 80% of your final grade
You are required to produce a portfolio of evidence on detailed analyses of repair maintenance and transportation considerations for a variety of projects covering different vessel types.
A successful portfolio should contain:
An overview introduction to the portfolio
Followed by the case studies 1 to 7
Identifying learning outcomes that fit each case 1 to 5
1. Assess the maintenance requirements of various vessels.
2. Determine the structural repair status of various vessels.
3. Derive appropriate structural repair requirements for various vessels.
4. Assess a wide range of vessels’ transportation requirements.
5. Investigate various vessels’ storage options.
Closing statements
Due date is 8th July 2011 Hand in to Student Central
Lecturer Marine Technology Richard Wilson
Email rwilson@unitec.ac.nz
Work Phone 815 4321 ext.8700
Office Location building 107
Repair and Transportation
Portfolio of evidence
This assessment is worth 80% of your final grade
You are required to produce a portfolio of evidence on detailed analyses of repair maintenance and transportation considerations for a variety of projects covering different vessel types.
A successful portfolio should contain:
An overview introduction to the portfolio
Followed by the case studies 1 to 7
Identifying learning outcomes that fit each case 1 to 5
1. Assess the maintenance requirements of various vessels.
2. Determine the structural repair status of various vessels.
3. Derive appropriate structural repair requirements for various vessels.
4. Assess a wide range of vessels’ transportation requirements.
5. Investigate various vessels’ storage options.
Closing statements
Due date is 8th July 2011 Hand in to Student Central
Lecturer Marine Technology Richard Wilson
Email rwilson@unitec.ac.nz
Work Phone 815 4321 ext.8700
Office Location building 107
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