FR2616739A1 - Boat skin of mixed wood/polyurethane foam/glass fibre construction - Google Patents

Abstract

Boat hull skin made of a wood/foam/laminate sandwich. The invention relates to a method for constructing a boat hull or deck skin combining three conventional methods, namely moulded wood construction, wood board construction and sandwich construction. It improves the intrinsic properties of the three original methods and eliminates their major defects. This skin (or this deck) consists of boards 5 aligned longitudinally, whose geometry exhibits, during bonding onto the ribs 4, grooves in which is bonded foam 12, then on the plane surface thus obtained a laminate of fabrics or wood. The device according to the invention is in particular intended for constructing sailing boat hulls and decks.

Description

 The present invention relates to a construction method of boat hull plating synthesizing 3 traditional processes, namely the construction of elastomeric wood, slatted wood and sandwich construction, or the combination of two or three processes between them.

 The elastomeric wood construction is practiced by gluing together in a different orientation by various deans (stapling, pressing, gluing under vacuum), slats (1) of sliced, sawn or plywood with a thickness varying from 1 to 6 n (Figure 1 shows this technique).

The first ply (2) of these wooden slats is either applied on a male ioule, in this case the plating can do without stiffeners
(self-supporting hull), or stretched on a set of healds (3) and members (4), which will remain integrated with the plating.

The main advantages are: - reduced tooling and knowledge - easy handling of the materials used - lightness, transverse and longitudinal solidity - easy repairability - pleasant aesthetics (interior all wood) - tightness - longevity - does not get tired. -
The major disadvantages are - does not allow all forms (request of soft curvatures) - very long to implement - the gluing and adjustment must be precise - does not allow to modulate the thickness of the plating according to the zones of
constraint (bow, cadenae, ballast, rudder) - does not have an excellent sound and heat insulation - can not receive without risk of delamination a plasticization of pro
tection or reinforcement - offers too much stiffness at punctual impact (floating wreck, ro
expensive, etc.)
The slatted timber construction is practiced by juxtaposing sticky and fixing by nailing (7), stapling or screwing, on a set of frames (4) and smooth, slats (5) of wood in the longitudinal direction. Figure 2 shows this technique.

The wooden slats are generally bouvetées (8). Figure 3 shows you this bouvetage.

The main advantages are those of the elbowed wood but with a reduced transverse stiffness and a more delicate repairability. On the other hand, longitudinal stiffness is accentuated, and the speed of implementation is improved.

The main weak point comes from the fact that passive laths are ju: taposées without flexible joint that can absorb the variations of thick due to the swelling of the wood as a result of a change of its hygrity rate (especially in the funds of the shell and in case of injury of the rev test protector, either outside or inside), and that the detachment of slats between them and their support can occur, av all known consequences (loss of tightness, strength, rotten lowering the market value of the product)
The polyester sandwich construction consists generally of a piece (9) of a light material (balsa "standing wood" or more generally polyurethane foam> sandwiched between two skins and fiberglass laminate + polyester resin (13) Figure 4 shows this construction.

 There is a great diversity of implementation (on me the male, or female, even without ioule) and used products that it would be tedious and useless to describe here.

The main advantages are the following - relative speed of implementation - allows all forms - excellent thermal and sound insulation - good stiffness of the plank - low maintenance - good longevity - lightness - excellent sealing.

The main disadvantages are - implementation of delicate materials (respect chia constraints:
ques) - interior of the boat to be reworked (lamination) - risk of delamination - requires the investment of a mold.

The following table compares these 3 processes with the process of the present invention, which will be described later.

COMPARATIVE TABLE OF DIFFERENT METHODS

<tb><SEP><SEP> Points <SEP> Wood <SEP> Comparison <SEP> Timber <SEP> Block <SEP> Sandwich <SEP> Presents
<tb><SEP> Polyester <SEP> Invention
<tb> Tools <SEP> and <SEP> Know <SEP> Excellent <SEP> Excellent <SEP> Good <SEP> Good
<tb><SEP> sessions
<tb> Efforts <SEP> Physics <SEP> Restricted <SEP> Restricted <SEP> Restricted <SEP> Restricted
<tb> Specific <SEP> Shapes <SEP> A <SEP> Curves <SEP> Curves <SEP> Curves <SEP> Curvatures
<tb><SEP> soft <SEP> and
<tb><SEP> bouchains
<tb><SEP>
<tb> Rigidity <SEP> Longitudinal <SEP> Good <SEP> Excellent <SEP> Very <SEP> Good <SEP> Excellent
<tb> Rigidity <SEP> cross-section <SEP> Excellent <SEP> Average <SEP> - <SEP><SEP> Very <SEP> good <SEP> Excellent
<tb> Points <SEP> low <SEP> Weakness <SEP> Separation <SEP> Delamination <SEP> Unknown
<tb><SEP> single <SEP> of the <SEP> slats
<tb><SEP> High <SEP><SEP><SEP>Ease><SEP> Isolation <SEP> Stiffness <SEP> Isol. <September>
<Tb>

<SEP> construc. <SEP> aspect <SEP> Int. <September>
<Tb>

<SEP> cost of <SEP> material <SEP> Medium <SEP> Medium <SEP> Medium <SEP> Medium
<tb> Move <SEP> type <SEP> Light <SEP> to <SEP> - <SEP> Medium <SEP> to <SEP> Light <SEP> to <SEP> Light <SEP> to <SEP>
<tb><SEP> Medium <SEP> Medium <SEP> Average <SEP> Medium
<tb> Tightness <SEP> General <SEP> Good <SEP> Average <SEP> Excellent <SEP> Excellent
<tb><SEP>
<tb> Ease <SEP> of <SEP> Finish <SEP> Medium <SEP> Medium <SEP> Medium <SEP> Good
<tb> Construction <SEP> in <SEP> Series <SEP> Small <SEP> - <SEP><SEP> Small <SEP> Series <SEP> Small
<tb><SEP> series <SEP> series <SEP> average <SEP> series
<Tb>

<tb> Points <SEP> of <SEP> Comparison <SEP> Wood <SEP> Molded <SEP> Wood <SEP> Latte <SEP> Sandwich <SEP> Presents
<tb><SEP> Polyester <SEP> Invention
<tb> Value <SEP> resale <SEP> Good <SEP> Low <SEP> Good <SEP> Very good
<tb> Risks <SEP> detachment <SEP> Low <SEP> - <SEP> trops <SEP> Medium <SEP> Low
<tb> delamination <SEP> big
<tb> Need <SEP> of a <SEP> mold <SEP> No <SEP> No <SEP> Yes <SEP> gen- <SEP> No
<tb><SEP> usually <SEP>
<tb><SEP> resistance to <SEP> shocks <SEP> Weakness <SEP> Weakness <SEP> Mean <SEP> Good
<tb><SEP> punctual <SEP> binding
<tb><SEP> Lateral
<tb><SEP> Combination of <SEP><SEP> Some <SEP> Sometimes <SEP> Low <SEP> Several
<tb> dice <SEP> of <SEP> setting <SEP> in <SEP> work <SEP> variants <SEP> associated <SEP> with <SEP> combined
<tb><SEP> wood <SEP> molded <SEP> sounds
<tb> Tarets <SEP> Very <SEP> good <SEP> Point <SEP> Inatta- <SEP> Inattaqua
<tb><SEP> low <SEP> quable <SEP> ble
<tb> IMPORTANT IEKLROUK
In nautical construction, the great diversity of the materials used and the "hands-on" projects make it imperative to define a process precisely, and it can be considered that, on the one hand, those described above have an average of at least a variant by c that built.

In addition, a hull of a boat remains a "work of art" in the sense that many parameters are not identifiable by scientific calculations and that good boats are the synthesis of complete knowledge, of a sometimes secular experience. scientific calculations.

BIBLIOGRAPHY- Reference may be made to the following documents: 1- Out of series N 4 Nautical Recreation: "Knowledge of construction n
dermis wooden boats "(extension work) 2- Modern methods to build a wooden boat (book tecl
nique) of Pierre Gutelle at EMOM 3- Structure and Construction of the sailboat TENON de Piere Aubry (book tec)
nic).

4- Out of series N010 Nautical Leisure: "Polyester construction in
joker "5- Hors série N016 Nautical Leisure" Alu-Acier-lnox "6- Haliotis drawn by JP BROUNS, Naval Architect
The present innovation results from the new combination of known means, it aims at eliminating the major drawbacks of the aforementioned methods and to retain their main advantages
The starting principle is that of the slatted wood construction, the advantages of which we know the main disadvantages being recalled: - weakness of the transverse connections - risk of detachment of the slats between them and their support as a result
of their volume variation
The invented method uses slats (11) whose section is shown in Figure 5, the shape of this section is not exhaustive, only the principle is described here In the triangular groove left free between the slats, are glued profiles of foam (12) and on the flat surface thus obtained is laminated a coating of glass fabrics (13) .These slats are obtained from triangular sections truncated on two angles to obtain two faces (26 and 27) which will ensure the connection with the other slats.The face between these two last will be located inside the hull, it alone will remain visible (28). The remaining two faces of the initial triangle (29) and (30) will receive the foam profile. To aid understanding, compare the invented process A as shown in Fig. (6) with a hypothetical similar construction B using a conne lath as shown in Fig. 7. The calculation shows that the volumes of wood and foam are identical .

10- Swelling
In A, the slats can accept a slight variation of thickness (we will see later the solution used to circumscribe this variation of thickness) because their dilation is distributed in the slack, material able to accept a slight compression.

 In B, the swelling varies the length L, and the su port (the chord 4) remaining invariable, the detachment is inevitable.

2 - Deadlock
In B the delamination stress of the foam on the bo is peeled.

 In A, this stress is shear which is much better, especially for a material such as foam.

30 Anchoring Surface
In B the anchoring surface of the foam on the coating: wood is equal to the anchoring surface of the laminate on the foam.

 In A this surface is doubled. So thanks to the advantages of 2 and 3; there is almost impossibility of detachment of the soft.

on its wooden support.

40 Compression
In B in case of compression of the plating (shock of any kind laminate skin only supports the foam material clearly pl compressible wood.

 In A this compression is distributed between the foam and the wood, the latter flush with the laminate.

3 - Moment of Inertia
The inertia of the profiles A is clearly superior to the B-profiles, hence a greater longitudinal stiffness of the plating.

6 - Weight
With equal surface area, the weights are almost identical.This statement of the 6 main points of comparison is sufficient to identify the technical novelty provided.

The advantages of this improved sandwich process will be described below: -Possibility to build a boat-free unit with a mold
competitive price, the labor time being not prohibitive.

-Very low technology investment and zero hardware investment
for construction sites already practicing wood construction and technique
emptiness.

- Radical elimination of the disadvantages of latte wood.

- Thermal and sound insulation very satisfactory (thermal insulation
that is not quantified, it can vary with the density of the soft
se, the wood species or species used, the latte profile chosen) - Possibility of using profiles of an aluminum alloy, assem
by welding, riveting, bonding or
limp.

- Possibility of modulating thanks to the laminate, the resistance of the plating according to the stress zones.

- Interior of the hull all wood.

- Very little return to work inside.

- The risks of delamination, the main weakness of sand construction
winch, are circumscribed.

- Improved overall strength, excellent longitudinal stiffness, very
sought for sailing yachts (resistance to stress induced
by the compression of the mast and the traction of the stays), and better
re punctual impact resistance.

RKWQUE
We can not quantify here the values of resistance train versale, longitudinal, nor punching, nor the weight of plating, nor value of the coefficient of thermal insulation.

Indeed, the richness of the process makes it possible to modulate, as a function of ch; that construction: - the profile and the material of the slats - the density of the foam - the sampling of the laminate and the nature of its fibers - the density of the network of frames (and of smooth if used) - the choice or not of a second sandwich as described using the fig
re (16) and his commentary.

Only the art of the architect combined with the experience of the site will define these choices.

 By way of non-limiting example, a prototype which has been made according to the invention will be described below.

Figure (8) shows this prototype.

On two ribs (4) glued laminated section 30x30 n, spaced axially axis of 400 n, providing a concave face (16) and a side vexe (17), and developed length of 2 m, linked between 20 x 40 n spacers, spaced axially in the axis of 400 MI, were bonded together, then glued and stapled on their support, a number of wooden slats (5) ( mountain spruce), as described in figure (8).

These slats were obtained using a fixed circular saw blade i clinable by sawing boards of thickness equal to the height of the prof slats, turning these boards to each pass (double siding).

Figure (5) describes the profile of the slats used.

Then sections of foam profiles (12), also obtained by sawing a plate of this material, were glued to the sawtooth surface perimeter generated by gluing the slats (14). The looseness of these section sections being 10 mm greater than the width of the double-sided adhesive, here partially shown (15), used far away, ie 40 n. The bonding pressure was obtained by the stapling veneer of soft, temporary ash slats 4 n thick, pre-glued with adhesive plastic film (not shown).
After rapid sanding of this peripheral seal, the foam profiles were dry pressed. Despite the small radius of curvature (about 400 n> of the concave surface (16) and the large radius (about 1200 ms) of the convex surface (17), only two different angles were necessary to ensure correct contact recommended by the adhesive agent (epoxy)
Note: This S-shape and its two radii of curvature represent
in its most tormented part, a hull section
sailing yacht type "Haliotis"
After marking with the colored marker of the two types of pro
wire, the double-sided adhesive was affixed to the peripheral seal
and then glue the grooves and
foam.

Then the air drainage system (18) (Scotch Brite, registered trademark) represented in the bonding phase of the glass fabrics was applied, then glued on the peripheral seal a plastic film (19), called "vacuum bag" ", having at its center an orifice connected to a pipe at the end of which was connected a vacuum pump providing a vacuum of 700 g / cm2 (20).

The depression plastered the foam in the gaps, and once the glue polymerized, a flat surface was obtained which was slightly sanded to receive 2 glass fabrics (21), also glued under vacuum.

Tests, certainly subjective, have shown the extreme lightness, stiffness and elasticity of this prototype deliberately slightly built, and we were surprised at the speed of implementation of materials.

APPLICATIOl INUSTRIELE
It will be recalled that the present invention only concerns the boat plating, and that the internal structures (smooth and oembru principally) and the connections of this plating to the other elements of the boat (keel, bridge, bow, sternum and transom) are not included in this innovation. These connections are part of traditional techniques. However, in order to describe a non-limiting industrial application, these elements will be mentioned.

 We will take the case of a dinghy sailboat hull weighed 10m by 3.70m, moving 6 tons, with return of port.

The architect recommends in mixed wood blockboard / molded wood construction, the following sampling:
The slats of wood (acacia in the living part, mountain spruce in the high) of thickness 12 n support 3 folds of sliced wood of 3 n, crossed at 45 o, a total thickness of 21 m The structure is composed of 30 x 30 n spacing strips spaced 500 n.Longitudinal stiffness is provided by a beam-keel, a 35 x 50 bauquiere, and by the mixed plating.

It is recalled that this construction is criticized and that experience has sometimes shown a separation of the wooden plank elongated on its lath support, these two planks working differently, either by mechanical stresses, or by hygrometric expansion stresses.

The initial idea is to repeat this process, improve its qualities and eliminate major defects.

CONSTRUCTION
On an alignment of jigs spaced by 500 mm, are fixed - the beam-keel, laminated-glued (its characteristics does not interest
not the present innovation) - a network of smooth sections 20 x 40 n spaced 400 n in the
short spokes (back of galbord) These provisional rails are now
bare with two crossed bungees (inner tube washers)
fixed on cleats.

With the help of this network of provisional rails, we will mold on pl; the frames by adopting the system of chords (4) deviated (fig which allows us - a great speed of execution - not to notch the frames (or the smooth if one chose
process in another construction)
The disadvantages are that, especially in the ends of the hull, the arrangements will have to take account of this deviation, and that the connection puts burns / keel will be longer execution.

The molded members are then planed to 30 n and stacked to receive later, in the living area of the hull stratification t protection, which will be discussed later.

The next step involves the described technical innovation. On a network of members are glued together and glued and stapled sr this support a set of slats and starting with the bulwark.

linking these slats at their ends on the bow and the stop table re, and later on the keel does not interest this process, it does a pel to traditional techniques.

The glue burrs are, on the inside, extended with the brush, as well as in the bottom of the grooves (epoxy process).

Staple will be as described in Figure 5.

The manufacture of wooden slats and foam profiles may be modified as described in the prototype.

Then we notice the angles formed by the juxtaposition of slats, with different foam jigs and identified by any means (we propc the color). These identical angle zones are identified and delimited by any means (eg color). We define a foam bonding surface (we can start with the back 1/4 of the shell), then c creates a flat surface delimiting the perimeter of this surface (we will relate to the description of the prototype).

Note: At the intended locations of cadenae, portholes, hull pass, etc.,
that is to say all the openings and zones of compression
Due to the accessories, we will replace the foam with profi
wood, in order to better withstand the constraints. (refers to
to traditional technique)
The foam stuck on the entire hull, dusted by suction, we will proceed to stratification (also refer to the traditional technique). For example, for our hull, we propose 5 fabrics of 300 g passing over the keel, coming to double the thickness in the bright works, carrying it to 10 fabrics, with the traditional gradients. Vacuum bonding will optimize the qualities of the laminate, save glue and save time when sanding.

Subsequent operations are not affected by the innovation.

Finally, we will proceed in the fund to a stratification of protection and waterproofing using a fabric of 300 g: a band overlapping each chord, a wider fabric on the plating and covering the overflow of the band.

Note: In the high humidity area, choose from
placing slats whose wood grain (22) is parallel to the
edged so that any swelling does not increase the lar
slat, favoring its detachment (Figure 10).

This innovation ceases at this stage of construction.

DEFINITION OF MATERIAL Col le: The glue used is exclusively an epoxy glue, for example
SR500 and SD 4007 system for wood / wood and wood / foam, and S
1500 + SD 2500 for laminate / foam, from Siconin (one of
less toxic of use).

Foam We will call mousse in the description any product suitable for compo
to be the soul of a sandwich, according to the traditional implementation
polyurethane foam, Damicelle PVC foam, registered trademark, o
standing wooden balsa).

Wood: Robinia (false acacia) is recommended in wetlands, d
high stress, where the weight is not a handicap and the ear
mountain peak (altitude above 1000m) for the high. Bie
obviously, this can not be exhaustive, and the facilities for
events often guide the choice among the very
species capable of satisfying the requirements.

Staples: Stainless steel, remain integrated in the structure.

Laminate: The laminate will use as binder epoxy glue and corner
fabric is glass fabric, with ad-hoc sizing, self
a modern fiber such as carbon fiber or d
kevlar (registered trademark), or the mixture of two of these fibers
or three (mixed tissue).

 Sometimes laminated wood sheets will be called laminated.

Aluminum Will be used an aluminum alloy (eg C51S from Al can) chosen from the very wide variety on the market, according to the criteria of ease of extrusion, mechanical qualities, and weldability Treatment (chemical stalling or mechanics) will be able to opti mize the attachment of the glue binding the foam
In summary, in the description only the terms: foam glue, wood, staples, laminate, aluminum inìum are used, in order to simplify the text.

DESCRIPTIONS OF THE DRAWINGS
Most remarks help to understand the description, suggest possible industrial uses of the innovation, but do not cover the scope of the innovation
Figure 11: Example of a profile with a connecting surface
arcs of circles. ha connection between foam profiles is ali
here with the connection between slats, so that more
plesse in (23), which makes it possible to compensate for variations
angle due to the curvature of the hull.

Figure 12: Here we gave greater insulation and increased iner
edge of the plating by a greater thickness.

Figure 13: This is a grooved board, which allows to win
time when laying, improves the interior appearance of the co
that (care of joint lines).

Figure 14: Here is a molded wood and not a tissue laminate
which may be of interest to a shipyard that does not wish to use
to use the technique of laminate and that of collage under vi
of.

Figure 15: This negative-relief relief requires the inclusion of the
foam when laying laths. The orientation of the fibers
wood will necessarily be parallel to the plating.

Figure 16: A second sandwich is formed on the first, in order to
improve insulation and stiffness.

Figure 17: Example of interlocking which increases the bonding surface in
latte and aligns perfectly these during installation. j
Figure 18: Example of interlocking aluminum profiles that avoids the
welding and its disadvantages (short, weakening
alloys, deterioration of any coating).

These profiles are glued (glue in black on the drawing) and
"clipped" in strength. They can be linked to a "structure
glue-laminated wood (keel, bauquière, bow and table
backward) by gluing and screwing
Figure 19: Connection of aluminum profiles by welding.

Figure 20: Idem
Figure 21: Example of connection with intermediate slat which can simplify
proud of the manufacture of the latter (identical grooves,
can reverse the slats to mounting) bonding surface to
lightened, increased insulation <used
for example in the boat's tops)
Figure 22: Glass, carbon or Kevlar fibers are inserted in
bottom of the grooves to improve the longitudinal rigidity.

Figure 23: The grooves are machined in the profiles, the foam is i
ensured when assembling slats. In (24) the profile is such that
in the parts of the convex hull, the flanks of the profile
tighten and ensure the pressure between slats and grips
also the foam.

 In (25) this profile is used in the concave parts.

Claims (4)

RZVINDICATIOIS 1- Boat hull construction method using as slats  associated with foam, characterized in that the slats are profi  and leave, when they are side by side, a space which is rem  folded by foam 2- Method according to claim 1 characterized in that the slats of  woods have a triangular profile. 3- Method according to claim 2 characterized in that the triangle of  profile is truncated on two angles to allow a larger con  tact between two adjacent slats. 4- Method according to claim 1 characterized in that several lat  are obtained by grooving a board and remain solidary  by the faces (26) and (27). 5- Method according to claim 1 characterized in that the slats are  profiles of an aluminum alloy, are hollow, and include on  the faces (26) and (27) of the male and female interlocking systems.