christmas
Member
After opinions on yacht construction, am I best with GRP double diagonal or ply and with the later 2 is it best if they are sheathed? what about maintainence costs???
Which is best GRP - Ply - Planked???
- Thread starter christmas
- Start date
Ships_Cat
Well-Known Member
I think in every respect the order is GRP-GRP-GRP with the others not even figuring if the boat wanted is available in GRP.
A diagonally "planked" boat built as a composite with GRP with the timber as the core (and I don't think that is the "double diagonal" construction you are referring to) is very good too and is commonly used for building one off boats where it is not practicable to mould the boat. Such boats are built here from a dense durable timber, in which case they may only be epoxy saturated inside, or with a light timber such as cedar as the core.
John
A diagonally "planked" boat built as a composite with GRP with the timber as the core (and I don't think that is the "double diagonal" construction you are referring to) is very good too and is commonly used for building one off boats where it is not practicable to mould the boat. Such boats are built here from a dense durable timber, in which case they may only be epoxy saturated inside, or with a light timber such as cedar as the core.
John
simonfraser
Well-Known Member
my ply epoxy boat is 6 years old and looks nearly new
great if you need a custom made job
and of course no osmosis
great if you need a custom made job
and of course no osmosis
Stemar
Well-Known Member
I think I'd agree with Ship's Cat. For a production boat, GRP is the best overall.
However, if you're thinking of building yourself, encapsulated ply has a lot going for it. There are some good plans for quite substantial boats out there using stitch and glue construction, which must be just about the easiest method for amateur construction.
The disadvantage is that even a relatively minor ding can mean the ply starts getting wet and needs to be completely dried out (or the wet bit replaced) before repairing the sheath
However, if you're thinking of building yourself, encapsulated ply has a lot going for it. There are some good plans for quite substantial boats out there using stitch and glue construction, which must be just about the easiest method for amateur construction.
The disadvantage is that even a relatively minor ding can mean the ply starts getting wet and needs to be completely dried out (or the wet bit replaced) before repairing the sheath
bigwow
Well-Known Member
For one off boats foam sandwich is the way to go, it's so much easier to use than encapsulated wood
aitchw
Well-Known Member
Have you looked at Cedar strip planking as well?
graham
Well-Known Member
It all depends on what type of boat your talking about.Are you talking about buying or building?
GRP will almost certainly have less maintenance costs.
Double diagonal produces immensely strong watertight hulls but can be difficult/expensive to repair or if water gets into any voids between the two layers of planking.For amateur construction it has the advantage that the planks are easilly handled by one person .But theres lots of them /forums/images/graemlins/smile.gif
Plywood can range from terrible stuff that wont last to extremely durable high quality material.Just because someone claims a boat has been built from "marine ply" doesnt neccessarilly mean good quality marine ply. On the plus side a plywood boat is easier to repair .
If building yourself ply is probably the quickest method but you will need a hand to fit large ply panels.
Epoxy sheathing is desirable for both forms of construction including decks and cabin superstructure. There tend to be more water ingress/rot problems in decks than in hulls.
GRP is usually the safest bet.Get a qualified surveyor to look at whatever you buy,it will be money well spent in the long run.
If self building in GRP the popular method is to build a temporary wooden mould to which foam panels are stapled the outside skin of grp is layed up and sanded/finished then the hull is turned over so the mould can be removed then the inside grp skin is layed up.
Sanding and fairing the outside of the hull is a huge soul destroying task.Anyone who claims it isnt hasnt tried it.Even with a gang of helpers its hard,single handed?
PS double diagonal is more commonly known as cold moulded in the UK. Good luck ,let uis know what you decide on.
GRP will almost certainly have less maintenance costs.
Double diagonal produces immensely strong watertight hulls but can be difficult/expensive to repair or if water gets into any voids between the two layers of planking.For amateur construction it has the advantage that the planks are easilly handled by one person .But theres lots of them /forums/images/graemlins/smile.gif
Plywood can range from terrible stuff that wont last to extremely durable high quality material.Just because someone claims a boat has been built from "marine ply" doesnt neccessarilly mean good quality marine ply. On the plus side a plywood boat is easier to repair .
If building yourself ply is probably the quickest method but you will need a hand to fit large ply panels.
Epoxy sheathing is desirable for both forms of construction including decks and cabin superstructure. There tend to be more water ingress/rot problems in decks than in hulls.
GRP is usually the safest bet.Get a qualified surveyor to look at whatever you buy,it will be money well spent in the long run.
If self building in GRP the popular method is to build a temporary wooden mould to which foam panels are stapled the outside skin of grp is layed up and sanded/finished then the hull is turned over so the mould can be removed then the inside grp skin is layed up.
Sanding and fairing the outside of the hull is a huge soul destroying task.Anyone who claims it isnt hasnt tried it.Even with a gang of helpers its hard,single handed?
PS double diagonal is more commonly known as cold moulded in the UK. Good luck ,let uis know what you decide on.
G
Guest
Guest
While in Brisbane I saw a wonderful example of a plywood diagonal strip boat. It looked just like a GRP boat but was made out of ~3" wide strips of ply in 2 layers diagonally crossed. The whole lot was put together with polyester and sheathed. It was a production MOBO.
The use of ply means you get the cored strength of a hull but without the continuous nature of core material. It was an old boat and one plank/strip, on the outer layer, had got water into it. They just replaced the plank as it was isolated from the rest of the ply by the GRP "glue" lines. After seeing the condition of the boat, that was older then myself, I now have a fresh outlook on real ply boat design.
Any construction method can be done very well or very badly. It was proved a few year ago, that however advanced the construction technology; it is never a substitute for the good engineering and design.
The use of ply means you get the cored strength of a hull but without the continuous nature of core material. It was an old boat and one plank/strip, on the outer layer, had got water into it. They just replaced the plank as it was isolated from the rest of the ply by the GRP "glue" lines. After seeing the condition of the boat, that was older then myself, I now have a fresh outlook on real ply boat design.
Any construction method can be done very well or very badly. It was proved a few year ago, that however advanced the construction technology; it is never a substitute for the good engineering and design.
christmas
Member
Thankyou all for the replies.
I am looking at purchasing a boat and see boats that suit my purpose in all the diff materials.
I am not a big spender looking at the yachts in the 25' -30' range.
Also what about engine I have always thought I would prefer a diesel in her but I am staring to thing I would be better with an outboard. What are peoples thoughts on this...
I am looking at purchasing a boat and see boats that suit my purpose in all the diff materials.
I am not a big spender looking at the yachts in the 25' -30' range.
Also what about engine I have always thought I would prefer a diesel in her but I am staring to thing I would be better with an outboard. What are peoples thoughts on this...
William_H
Well-Known Member
Don't be put off by osmosis it is not so hard to fix and certainly will never disable the boat. Polyester GRP has been around for a long time and for my money is the only way to buy secondhand.
Diesel engines as compared to outboard will command a better resail price and are more desirable for long mororing trips.
However a small diesel single cylinder is very noisy. Any inboard will take up a lot of usefull space and possibly give a smell. Diesels do need mainttenance and are expensive to repair.
Outboards do not usually have the driving power especially in a rough sea as the prop can be lifted out of the water. They are easily removed for repair and are usually outside on the transom saving space inside. So possibly diesel will be your choice but it depends on your sailing style almost 50/50. olewill
Diesel engines as compared to outboard will command a better resail price and are more desirable for long mororing trips.
However a small diesel single cylinder is very noisy. Any inboard will take up a lot of usefull space and possibly give a smell. Diesels do need mainttenance and are expensive to repair.
Outboards do not usually have the driving power especially in a rough sea as the prop can be lifted out of the water. They are easily removed for repair and are usually outside on the transom saving space inside. So possibly diesel will be your choice but it depends on your sailing style almost 50/50. olewill