Are Cats Made from Duflex Panel Kits Strong ?

[Fard12]

Originally Posted by 44'cruisingcat

The 3 spirited 380's I have seen all have balsa as the core in the moulded parts both above and below the waterline.

As for the experiment conducted by TCP's editor, that has Duflex boat builders simply scratching their head. It's well known and accepted that the weave on a Duflex panel should be filled before painting. It's a simple matter of applying a runny epoxy glue mix with a squeegie or trowel. Why someone would go to that much trouble to "prove" what is already well known it is a mystery.

The spirited 380's hulls (Canoes are made in a female mould infused)
The flat panels are then fitted to the hulls bottoms.

[Esprit Marine]

Originally Posted by olliric

Is the kit for the Spirited 480 available certified according to CE standards? If so what are the differences in cost and weight?

Indeed the Spirited 480 is available CE certified. Difference in kit weight has not been worked out by Craig Schionning yet, but with extrapolation from the 380 it should be around 400 kg.

Originally Posted by olliric

Kit boats and insurances companies:
How do insurance companies value the kit boat to issue coverage? The fact that the boats are not built meeting recognized standards (i.e CE or classification societies') can be a reason for denial or restriction of coverage?
Cheers

The kit boats can be built to recognized standards, and are covered by the EC Recreational Craft Directives. You can have them CE certified if you follow the ISO standards.

[olliric]

Originally Posted by Esprit Marine

Indeed the Spirited 480 is available CE certified. Difference in kit weight has not been worked out by Craig Schionning yet, but with extrapolation from the 380 it should be around 400 kg.



The kit boats can be built to recognized standards, and are covered by the EC Recreational Craft Directives. You can have them CE certified if you follow the ISO standards.

Can the CE version be considered a stronger boat or it's just a matter of complying to some bureacrat formula?

I am considering building the boat in Brazil with the help of two boat craftsmen. What would be involved time and cost wise in following the ISO standard and to have the CE certification?

[44'cruisingcat]

Originally Posted by Fard12

The spirited 380's hulls (Canoes are made in a female mould infused)
The flat panels are then fitted to the hulls bottoms.

And the cores of the hull canoes are still balsa or has that changed?

[44'cruisingcat]

Originally Posted by olliric

Well, it's not very reassuring to know that the only safe barrier to stop the water from getting to the balsa is the pre-painting preparation. The coat is likely to be not very thick and could be removed by scratching against something sharp.
However, I guess that if the construction is done properly and with very careful use, water can be left out of the core.

A Duflex Oram 44C was sailed onto the rocks at Great Keppel Island at 5-6 knots. There was no damage to the hulls. I can't see that any other type of construction would have fared better.

The only damage to the boat was to the rudders which had kicked up on impact as they were designed to, but were dragged back into the lowered position when the boat was reversed off the reef. One of them broke off later, which was only noticed because the autopilot was working harder than usual.

[Esprit Marine]

Originally Posted by 44'cruisingcat

And the cores of the hull canoes are still balsa or has that changed?

The core of the underwater hulls of the Spirited 380 is 150 kg/sqm balsa, covered with 1200 gsm biax. Indeed you could prefer monolithic underwater hulls, but this would add around 600 kg hence 18% of the total lightship weight.

At the end what you want is up to you, a performance cruiser or a roomy condomaran, but everything is a compromise...

[Esprit Marine]

Originally Posted by olliric

Can the CE version be considered a stronger boat or it's just a matter of complying to some bureacrat formula?

I am considering building the boat in Brazil with the help of two boat craftsmen. What would be involved time and cost wise in following the ISO standard and to have the CE certification?

The purpose of the ISO standards is to give some minimum safety rules for boats sold on the European market. Most of the large European builders are part of the ISO commissions. And yes, the CE version can be considered stronger, as skin and thicknesses of hull panels have been increased.

Apart from the cost increase in the kit, the major impact will be the time you will need to spend with your CE consultant and the CE certification organisation.

[Nordic cat]

Originally Posted by Esprit Marine

The purpose of the ISO standards is to give some minimum safety rules for boats sold on the European market. Most of the large European builders are part of the ISO commissions. And yes, the CE version can be considered stronger, as skin and thicknesses of hull panels have been increased.

Apart from the cost increase in the kit, the major impact will be the time you will need to spend with your CE consultant and the CE certification organisation.

Most of the work required to conform to the RCD has to be done by the designer.

Make sure you know what you are doing if you buy a kit boat from a designer who has not done this before! There are several examples of boats that were supposed to comply, but never got through the approval, as the designer loses all interest once he has the money.

Things like the size of cockpit drains, stability calculations, scantlings etc all have to comply, as do all the fittings etc. used.

If you are building outside the EU, you will have extra costs to get all the equipment required, even hoses, wiring etc. All these components have to come with a CE approval, and the certificates have to be on hand for the surveyor to see and approve.

Don't take the kit salesmans word for "how easy" it is to do this. It's not a big issue if the designer has done his work, but many designers don't know -so be careful. Maybe a good idea to get the CE surveyor in on the job before you sign on the dotted line, so he can ensure that the designer has done the job he needs to.

And Yes, the RCD compliant boat will be a bit heavier and stronger, as many of the Australian designed Duflex kits are not compliant regarding skin strengths.....

Alan

[olliric]

Originally Posted by Nordic cat

Most of the work required to conform to the RCD has to be done by the designer.

Make sure you know what you are doing if you buy a kit boat from a designer who has not done this before! There are several examples of boats that were supposed to comply, but never got through the approval, as the designer loses all interest once he has the money.

Things like the size of cockpit drains, stability calculations, scantlings etc all have to comply, as do all the fittings etc. used.

If you are building outside the EU, you will have extra costs to get all the equipment required, even hoses, wiring etc. All these components have to come with a CE approval, and the certificates have to be on hand for the surveyor to see and approve.

Don't take the kit salesmans word for "how easy" it is to do this. It's not a big issue if the designer has done his work, but many designers don't know -so be careful. Maybe a good idea to get the CE surveyor in on the job before you sign on the dotted line, so he can ensure that the designer has done the job he needs to.

And Yes, the RCD compliant boat will be a bit heavier and stronger, as many of the Australian designed Duflex kits are not compliant regarding skin strengths.....

Alan

Thanks for the info. Do you know anybody that did go through the process of getting the CE approval?
Hopefully having a CE approval should be beneficial if one wants to sell the boats or insure it with a European company.
One of my fears is to spend a lot of time and money for a boat that can be difficult to sell if one has to. Given the general belief on the balsa cored hull construction, a duflex boat can already be hard to sell outside Australia.

[Robertcateran]

Originally Posted by Nordic cat

Most of the work required to conform to the RCD has to be done by the designer.

Make sure you know what you are doing if you buy a kit boat from a designer who has not done this before! There are several examples of boats that were supposed to comply, but never got through the approval, as the designer loses all interest once he has the money.

Things like the size of cockpit drains, stability calculations, scantlings etc all have to comply, as do all the fittings etc. used.

If you are building outside the EU, you will have extra costs to get all the equipment required, even hoses, wiring etc. All these components have to come with a CE approval, and the certificates have to be on hand for the surveyor to see and approve.

Don't take the kit salesmans word for "how easy" it is to do this. It's not a big issue if the designer has done his work, but many designers don't know -so be careful. Maybe a good idea to get the CE surveyor in on the job before you sign on the dotted line, so he can ensure that the designer has done the job he needs to.

And Yes, the RCD compliant boat will be a bit heavier and stronger, as many of the Australian designed Duflex kits are not compliant regarding skin strengths.....

Alan

But seem quite strong enough for Australian conditions. Didn't know that the conditions in Europe were worse than Bass Strait or Cape Leuwin

[Nordic cat]

Olliric: I don't know of any Duflex kit builds that are CE/ISO compliant, ask the kit supplier for a documented build, if he hasn't got one where you can speak to the builder directly, then stay away.


Robertcateran:

As with all standards, they are a compromise, and I'm sure that there will be a certain degree of over engineering in some cases, as you say, the exsisting boats seem to be doing fine.

The CE approval system is based on developing ISO standards which are global standards that can be adopted by individual countries. In a few years time we can expect the majority of countries to have adopted these standards, whether we like it or not.

When it comes time to sell your boat, there is a risk that you will not be able to sell the boat in more regions than today. It's just a fact of life, whether we like it or not, so we just have to know what the risks might be and decide for ourselves... just like balsa/foam or poly/vinyl-ester/epoxy.

Alan

[Robertcateran]

Originally Posted by Nordic cat

Olliric: I don't know of any Duflex kit builds that are CE/ISO compliant, ask the kit supplier for a documented build, if he hasn't got one where you can speak to the builder directly, then stay away.


Robertcateran:

As with all standards, they are a compromise, and I'm sure that there will be a certain degree of over engineering in some cases, as you say, the exsisting boats seem to be doing fine.

The CE approval system is based on developing ISO standards which are global standards that can be adopted by individual countries. In a few years time we can expect the majority of countries to have adopted these standards, whether we like it or not.

When it comes time to sell your boat, there is a risk that you will not be able to sell the boat in more regions than today. It's just a fact of life, whether we like it or not, so we just have to know what the risks might be and decide for ourselves... just like balsa/foam or poly/vinyl-ester/epoxy.

Alan

Hi Alan,
I heartily agree with your post. We need to look at the options and decide what path to take.
I plan to build with basalt fiber over polypropylene honeycomb. I plan to build a Harryproa. I have no idea what the resale price is but if I start worrying about selling it I won't be building the boat I want. I don't care about the possibility of print through, I have no desire to sell the boat overseas, and generally do not have a desire to sail anywhere but within a thousand miles or so of Australia. I figure it will take at least twenty years to explore this area and by then I will be starting to feel my years. For A$50grand I should be able to get a boat on the water with the bare minimum comforts and obligitory safety items. If I started to worry about overseas regs, the price would probably double, I wouldn't get to build it, and if I did get to build it. it would ruin much of the joy in the building

[johny1973]

"There are hundreds of Duflex boats around the world. AFAIK none have had problems with wet cores. But why not contact ATL and ask them? ATL Composites - engineering resin foam waterproofing carbon fibreglass adhesive fairing boat repairs structural fibreglass."


I know of a number of Duflex boats which have suffered rotten/soggy balsa cores as a result of water entering via a deck fitting etc, and spreading, even transiting z joins on a schionning in QLD.

And one Oram that a large void in the core was located prior to painting, just two laminates of glass with a veneer under each and no balsa at all.

ATL would be the last place who are going to volunteer information on core failures (for what ever reason) on there product.

[44'cruisingcat]

If deck fittings are improperly done then water can get in. There is not yet a completely foolproof boatbuilding material. Having said that I looked into Duflex pretty extensively and never heard about these boats,

Interestingly, neither has Bob Oram heard about this large void in the core of one of his boats. And he keeps in pretty close touch with all the builders of his boats.

I've seen places where there are small voids in the balsa, but these are always filled with epoxy.

For a void to be so large that the epoxy didn't fill it would make it immediately visible to anyone. The laminates would also have sagged under the press.

[catty]

Originally Posted by 44'cruisingcat

If deck fittings are improperly done then water can get in. There is not yet a completely foolproof boatbuilding material. Having said that I looked into Duflex pretty extensively and never heard about these boats,

Interestingly, neither has Bob Oram heard about this large void in the core of one of his boats. And he keeps in pretty close touch with all the builders of his boats.

I've seen places where there are small voids in the balsa, but these are always filled with epoxy.

For a void to be so large that the epoxy didn't fill it would make it immediately visible to anyone. The laminates would also have sagged under the press.

What actual experience has bob got? Is bob a qualified naval architect? Is bob a qualified engineer?. Is bob a qualified shipwright?. Which other designers out there think a large balsa cruising cat with a flat bottom is a good idea? Do designers in Europe and north America think balsa below the waterline is a good idea? Or is bob just a lovely guy who likes to draw boats to the best of his ability.