FR2555119A1 - Method of treating the surface of the hull of a commissioned ship - Google Patents

Abstract

When a ship has remained in service for many years, the outside of its hull is both rusty and encrusted with marine organisms, which increases its fuel consumption. When the rusty and encrusted exterior of the hull of the ship is treated to reduce the roughness of the surface and when a new coating is applied over an area of between one and three tenths of the length existing between frames from the stem, the saving in fuel (i.e. the percentage reduction in kl/km) increases even though the treatment is limited. In other words, the above treatment produces a fuel saving equivalent to that obtained when the entire surface of the ship is treated.

Description

 The present invention relates to methods of treating the surface of the outer shell of a ship in service.

 When a vessel has been in service for years, its outer hull is rusted, and also encrusted with marine organisms, which reduces the vessel's speed and increases fuel consumption.

 Usually, a ship that is in such a state is repaired by partially removing the rust and the organisms which incrust it by sanding, then by coating the sandblasted surface with an anti-corrosive paint and a coating. antifouling paint.

 Recently, because of the considerable cost of fuel oil, and since sand-blasting repairs have a certain efficiency, but result in high fuel consumption during the journeys following these repairs, it has been common practice to put the vessel in the bilge dries after it has sailed for a given period of time, then sand the entire outer hull below the waterline to remove rust and marine organisms, following which on all this surface the antifouling paint, which in other words, is called, in practice, technique of integral sandblasting.

 In this case, the fuel consumption can be reduced. However, since a large surface area of the outer shell is treated, the result is a high cost for the repair.

 Therefore, the purpose of the present invention is to provide a method for treating the surface of the outer hull of a vessel in service which allows a saving in fuel equivalent to that obtained in the case of the treatment of the entire surface, while being, by contrast, comparatively more convenient and less expensive.

 For this purpose, according to the invention, such a method is characterized in that tra-ite the outer hull of the ship over a range of one tenth to three tenths of the length existing between pairs, from the bow, in order to reduce the surface roughness, then a coating is applied again to the surface thus treated.

 In order to reduce the surface roughness, the outer shell can be treated by means such as a disk sandblaster, a grid blast, a wet sanding and a normal sanding.

 The normal sanding process is clearly preferred to obtain a well polished surface, which can be done in a relatively short period of time.

 With regard to the basecoat of the new coating, chlorinated rubber, tar vinyl, epoxy tar, epoxy, etc. can be used, but the tar and epoxy tar mixtures are preferred.

 With respect to the antifouling surface layer, chlorinated vinyl paints and organic polymer-based paints can be applied, but self-polishing antifouling paints are most preferred.

 As an example of such antifouling paint of the self-polishing type, mention may be made of the paint based on tributyltin (metha) acrylic copolymer.

 According to the invention, and as already indicated, a new coating is treated and applied to a reduced area of the surface of the outer shell. As a result, despite this reduced treatment area, it is possible to save on fuel consumption and to go through only a short repair period in dry dock, with also an advantage at the level of the engine. increased service in navigation, while a significant reduction in the cost of repair can be achieved compared to the full-treatment coating technique.

 We will now give real test examples of the invention and more specifically real examples 1 to 3 and comparative examples 1 and 2.

 The vessels indicated in Table 1 below have been operated for a certain period of time.

The outer hull areas of these vessels, shown in the table, were then sandblasted, and the areas of the sandblasted surfaces were coated with antifouling paints also shown on the chart.

 The average surface roughness of the treated areas of the shells is, before and after treatment, as indicated in the table.

 The vessels thus treated and coated were then put into service during the periods indicated in the table. The kl / km was obtained before surface treatment, the kl / km after treatment and the percentage reduction in kl / km of these vessels. The results obtained are those shown in Table 1.

TABLE 1

Assay <SEP> Real <SEP> Assay <SEP> Comparative <SEP> Assay <SEP> Real <SEP> Assay <SEP> real <SEP> Assay <SEP> comparative
<tb> Example <SEP> 1 <SEP> Example <SEP> 1 <SEP> Example <SEP> 2 <SEP> Example <SEP> 3 <SEP> Example <SEP> 2
<tb> Type <SEP> of <SEP> navira <SEP> Transport <SEP> of <SEP> Transport <SEP> of <SEP> Transport <SEP> of <SEP> Transport <SEP> @ stolen
<tb> CHERRY <SEP> Mineral / Petroleum @ <SEP> Mineral / Petroleum <SEP> Mineral / Peratole <SEP> from <SEP> Bulk
<tb> DE
<tb> Weight <SEP> in <SEP> heavy
<tb> CHARCES <SEP> (tons) <SEP> 165.000 <SEP> 248.000 <SEP> 158.000 <SEP> 92.000 <SEP> 87.000
<tb> DU <SEP> SHIP
<tb> Length <SEP> other
<tb> SOUTH <SEP> A <SEP> couples <SEP> (on <SEP> m) <SEP> 289 <SE> 320 <SE> 270 <SE> 263 <SE> 251
<tb> THE TEST
<tb> Puissonce <SEP> continues
<tb> maximum <SEP> (in <SEP> CV) <SEP> 30,800 <SEP> 36,000 <SEP> 32,000 <SEP> 18,400 <SEP> 20,300
<tb> Surface <SEP> of <SEP> in <SEP> parto <SEP> e @ bled <SEP> (the <SEP> length <SEP> other
<tb> METHOD <SEP> couple <SEP> cat <SEP> equivalent @ nte <SEP> 0-30 <SEP> 0-10 <SEP> 10-20 <SEP> 20-30 <SEP> 30-40
<tb> to <SEP> 100 <SEP> and <SEP><SEP> digits
<tb> co-presenting <SEP> the empl @
DE <SEP> Cement <SEP> to <SEP> From <SEP> of
<tb> the bow)
<tb> TREATMENT <SEP> Size <SEP> anti
Epoxy-tar <SEP> Epoxy-tar <SEP> Rubber <SEP> chlor @ <SEP> tar-vinyl <SEP> Epoxy-tar
<tb> Type <SEP> corrosive
<tb>
<tb> paint <SEP> Paint <SEP> anti- <SEP> Type <SEP> Type <SEP> Type <SEP> Type
<tb> Rubber <SEP> Chlorinated
<tb> fouling <SEP> self-polishing <SEP> self-polishing <SEP> self-polishing <SEP> self-polishing
<tb> Roughness <SEP> average <SEP> before
<tb> 402 <SEP> 450 <SEP> 480 <SEP> 395 <SEP> 478
<tb> RUGOSITY <SEP><SEP> treatment of <SEP> surface
<tb> (in <SEP> microns)
<tb> DE <SEP> SURFACE
<tb> Roughness <SEP> mean <SEP> after
<tb> HESU @ EE <SEP> tightly <SEP> of <SEP> surface <SEP> 262 <SEP> 35 @ <SEP> 375 <SEP> 290 <SEP> 315
<tb> (in <SEP> microns)
<tb> kl / km <SEP> av @ nt <SEP> tralination <SEP> of <SEP> surface <SEP> 0.1 <SEP> 0.108 <SEP> 0.105 <SEP> 0.089 <SEP> 0.084
<tb> CONSOHHATION
<tb> kl / km <SEP> after <SEP> tr @ i
OF
<SEQUENCE><SEP> Surface <SEP> 0.090 <SEP> 0.107 <SEP> 0.101 <SEP> 0.085 <SEP> 0.0 @ 3
<tb> COH @ USTI @@ LE
<tb> reduction <SEP> on <SEP> for
WHEN <SEP><SEP> contage <SEP> of <SEP> kl / km <SEP> @, 10 <SEP> 0.91 <SEP> 3.59 <SEP> 4.24 <SEP> 1.43
<tb> SAVIRE <SEP> IS
<tb> P @ rinde <SEP> (in <SEP> months)
<tb> at the <SEP> course <SEP> of the <SEP> r @@@ vé <SEP> 12 <SEP> 12 <SEP> 12 <SEP> 12 <SEP> 12
<tb> EN <SEP> CHARGE
<tb> of <SEP> data
<Tb>

Claims (1)

 CLAIM  A method of treating the surface of the outer hull of a vessel in service, characterized in that it consists in treating this surface of the outer hull of the vessel on a portion corresponding to an area one tenth to three tenths of the length existing between pairs, from the bow, to reduce the roughness of the surface, then to apply a new coating on the surface thus treated.