HULL MATERIALS....3D Printing. Croatian Motion.

[Robert Grubisa]

Hi Graham,

I am interested to know what is the outcome of the discussion here. A lot of a time and effort have been spent here, much information have been shared. CRO proposal is defeated on the last IOM ICA General Assembly, so what will be the next step?

Just for note, any IOM 3D printed hull which is printed using the thermoplastic material with glass fibres is illegal. Well, if this is the will of the majority, let it be...

Lester invited people to answer on his questions. Some replies have been received and the majority is against the honeycombed construction. Honeycombed construction is prohibited in the Croatian motion proposed.

Personally, after all this discussion I don't see the problem with the original CRO proposal wording.

All the best

Robert

[Art Prufer]

The original 3D printing proposal also changed the rules for non-3D printed boats. That is why it failed.
If you propose changing more than one thing at a time, I suggest submitting a separate proposal for each change.
That way both changes are not defeated when only one fails.

[Robert Grubisa]

Hi Art,

Could you please explain what has been changed for the non-3D printed boats in the CRO proposal except the proposed wording is changed in order to clearly allow all sorts of gel coats, resins with pigments and other additives as well as additives to thermoplastics which was not clear in the current wording of the class rules?

Please, let us know if there is any loophole in the proposal which can be exploited to make better non-3D printed hull than it is currently allowed?

Regarding the possible two submissions instead of the proposed one, it is much easier to make a harmonized technical sound wording which covers the whole hull material rules chapter.

All the best

Robert Grubiša
CRO 68

[John Ball]

Hi Robert,
It is disappointing that you would go back to square one and start the discussion all over when we seemed to have reached a consensus on this thread that many would support a change that left the current materials alone and just made the minimum of line item changes that would improve 3D printing.

You ask what is wrong with your proposal – my view is that it changes the philosophical structure of the Materials section in a very significant way – with possible ‘unexpected’ consequences.

The current IOM class rule is a Closed Rule – and the Materials section follows that philosophy by listing only what is permitted. Your proposal changes the Materials Section completely to an ‘Open’ style, by saying all materials are permitted except those that are not permitted.

Here is an example – under your new wording, how would Texalium be treated?

John

[Robert Grubisa]

Hi Hiljoball,

I am not starting the discussion all over and I don't see reached consensus to leave the current wording for non 3d printing hulld as it is now.
You mentioned that the proposal "changes the philosophical structure of the Materials section in a very significant way – with possible ‘unexpected’ consequences." Sorry, this sounds to me like some political phrase

It is difficult, if not impossible, to list only what is permitted in the Material section and therefore the proposed wording has been made restricting the fibre reinforcement material as a crucial one.

Texalium will be permitted as fiberglass-based fabric that has a proprietary finish and a thin coating of aluminum. Modulus of elasticity of the aluminium content is just below the best glass products.

---------------------

I contacted Graham, who started this thread, to hear his ideas how to materialize all the discussion here in the useful way (new proposal, new voting, etc.) I am sure that he will explain his thoughts when he will be ready to do so. I simply don't want to quote here our communication without his consent.

Best regards

Robert Grubiša
CRO 68

[Art Prufer]

I believe the proposal failed because it was labelled as a change for 3D printing materials, but included changes for non-3D printed materials.
There was a very detailed explanation in Appendix C section 3 around the reasoning for the 3D materials change, but was very little mentioned regarding the change to the existing permitted materials (bolded text below).

3) Reasoning for the proposed IOM Class Rule
The purpose of the proposed IOM Class Rule changes is to formulate a construction materials section of the rules having in mind the original intention of the IOM Class - to permit home built boats to compete structurally with mass produced boats and at an attractive cost – in order to enable good quality hulls to be obtained from a wider variety of sources than at present.
Currently, only a very small percentage of home-built boats now exist in the class. Those that are home built are invariably used by their owner/builders at their own club. Boats competing at the highest level come from a relatively limited number of builders. The class will be much more robust if sources of good quality hulls are available from a larger number of sources and from a larger number of designers.
The relatively small number of builders seen to provide competitive boats, relative to the number of countries where they are raced, means many hulls are imported at a cost that is large in comparison with their value. The absence of locally produced boats that are seen to be competitive works against local growth of the class.
Whereas few individuals have the skills or time to create their own hulls from timber, many are now in a position to create a hull by 3D printing. Currently, according to a recent interpretation, glass fibres may be used in traditionally laminated hulls, and in structures made using additive manufacturing involving resin, but may not be used in 3D printed hulls. This is an unreasonable restriction on a low-cost method of construction which is available to many who do not possess the construction skills of earlier generations.
Proposed class rule changes are permitting the use of glass reinforced thermoplastic material used for 3D printing of the IOM hulls. Fibre materials with modulus of elasticity higher than glass are still prohibited so the boat builders using glass reinforced resin don't need to invest in new materials and building techniques.
The proposed rule is simpler to understand than the existing. It is expected that this rule changes will allow more home builders keen in 3D printing of hulls to build their own or others design. Also 3D printed prototype designs could be tested against the molded hulls before the investments in the plug and mold have been made. In addition, all sorts of gel coats, resins with pigments and other additives as well as additives to thermoplastics are clearly permitted which was not clear in the current wording of the class rules.

I did not see any discussion with the IOM global community regarding this proposed change, at least not on this forum or on any of the other IOM sailing forums.

I must agree with John that the proposed change to all permitted materials (not just for 3D printing) changes the fundamental nature of this section from a closed rule to an open rule, possibly inviting new & unexpected challenges to this rule.

Only fix what is broken. No need to change the whole rule for the sake of some minor wording updates for permitted resin additives.

[John Ball]

This topic has been presented by CRO again for the 2022 General Meeting, basically the same motion that was defeated at the last General Meeting.

It is a shame that the movers did not follow the suggestions offered here for a more acceptable approach - just modify the section on plastics, and leave the rest of the class materials section as-is.

John

[Olivier Cohen]

In fact, exactly the same proposal.

Yes I don't understand neither.

[John Ball]

The vote on this is coming soon - if you like the current closed materials list for normal construction, and think that the motion to amend materials for 3d printed hulls should have been placed in the the line item D2.1.8 Thermoplastics then vote AGAINST this item.

This motion is exactly the same as the one defeated at the last AGM, and the proposers were given lots of advice in this thread to place their request into D2.1.8 and not disturb the rest of the class materials, yet they have ignored this advice.

John

[Robert Grubisa]

As far as I know, the main problem with the proposal on the last AGM was a fact that motion has not been explained enough, etc. Therefore, GBR representative Graham Elliot started this thread to hear the opinion of the guys using 3D print. He, and many others, let us know that there is not much wrong with the original CRO proposal.

Having now all data collected here which was not available before the last voting, it seems wise to offer to the IOM community to vote it again.

John and others worried about this proposal, why you don't help us all and asked your NCA to propose the motion which will solved this issue on this AGM? IOM ICA VC Technical is also silent...

The conclusion of the IOM Interpretation 2020-IOM-1 is clear that Class Rules D.2.1 should be improved.

Also, an interpretation is requested when it is not clear (to a designer, builder, measurer, class association or certification authority) how a class rule shall be interpreted. When an interpretation is issued it should be kept in mind that the interpretation is valid until the class rules are changed or for two years maximum only. The purpose of this last rule is that two years gives sufficient time to consider if the effect of the interpretation is a) desirable or b) undesirable. Depending on the decision or choice (a or b, by the IOM ICA) the class rules can be revised accordingly.

[Art Prufer]

Now that this motions has passed and come into effect, it is clearly lacking in specifics and is quite ambiguous.
There is no mention of what number is used for the modulus of elasticity for the many types of fiberglass.
Nor is there any mention of what specific chart will be used to determine the modulus of elasticity of the material wanting to be used to replace FG.
There is a new discussion in the IOM FaceBook group regarding using basalt cloth for hull construction.
https://www.facebook.com/groups/iomsail ... 7565190417
Using the highest Young's number found for FG and the lowest number found for Basalt cloth, this material should be allowed.

[Art Prufer]

The conclusion of the IOM Interpretation 2020-IOM-1 is clear that Class Rules D.2.1 should be improved.

Also, an interpretation is requested when it is not clear (to a designer, builder, measurer, class association or certification authority) how a class rule shall be interpreted. When an interpretation is issued it should be kept in mind that the interpretation is valid until the class rules are changed or for two years maximum only. The purpose of this last rule is that two years gives sufficient time to consider if the effect of the interpretation is a) desirable or b) undesirable. Depending on the decision or choice (a or b, by the IOM ICA) the class rules can be revised accordingly.

I agree,Class Rules D.2.1 should be improved.
Essentially what IOMICA has done is changed a closed class rule to an open class rule. From only wood or fiberglass to any material as long as it's not stiffer than fiberglass. There are no specific numbers given for the modulus of elasticity or of what type of fiberglass, nor is there a source for the chart to be used to determine the GPa of the building material in question.
As they are written now, technically all materials must be approved by an interpretation, which as you have stated, is only valid for 2 years.
Here is just one example using the open source Wikipedia:

There are many other sites which provide conflicting information for what is shown above.

[Mike McPherson]

forgive a silly question from someone new to all this
I have read the rules but why are cellular structures are so frowned upon?

please help me understand

many thanks
Mike

[Bruce Andersen]

rules must be enforceable and therefore, structures that can only be examined by destructive testing (like the interior of a honeycomb structure) should not be allowed

lets not get into the rule that specifies what grades of aluminum are allowed

[Mike McPherson]

rules must be enforceable and therefore, structures that can only be examined by destructive testing (like the interior of a honeycomb structure) should not be allowed

lets not get into the rule that specifies what grades of aluminum are allowed

@Bruce
I understand the "must be enforceable" part, but if honeycomb were to be allowed, there would be no infringement so nothing to verify
so what is it intrinsically about honeycomb that ruffles so many feathers?
it can't be a cost issue (keep it affordable so anyone can build one)
if it is purely structural or strength related, then Darwin will ensure that its use will fall by the wayside, surely?

or is it that there are so many builds out there that DON'T use honeycombed material, and they would all be suddenly disadvantaged?

thanks
Mike

PS and then I have to wonder about carbon fibre, which is becoming a common build material . . .

[Art Prufer]

[/quote]

or is it that there are so many builds out there that DON'T use honeycombed material, and they would all be suddenly disadvantaged?

thanks
Mike

PS and then I have to wonder about carbon fibre, which is becoming a common build material . . .
[/quote]

THIS ^^^

The IOM is a decades old class with a well established set of closed class rules, meaning if it's not specified in the existing class rules, then it is not permitted. In the past few years there have been a number of rule changes to allow new and improved items, some of which puts existing boats at a disadvantage. This defeats the original intent of the class by requiring older boats and designs to be upgraded to remain competitive.
There are other 'developmental' classes out there for those that want to push the envelope and participate in the 'race to the top' or 'space race'.

[Mike McPherson]

ah thanks
that does make sense now
appreciate your patience!