A method for reinforcing a fouling control coating, comprising the steps of: (i) forming a reinforcing coating (O) by applying and curing a reinforcing coating composition [o] comprising - an organopolysiloxane (AO) having two or more silanol groups or hydrolyzable groups in the molecule, and - a pyrithione salt compound (BO) of formula [I]: wherein R 1 each independently is H, optionally halogenated C 1-6 -alkyl, C 3-6 -cycloalkyl, C 2-6 -alkenyl, C 6 -aryl or C 1-6 -alkoxy, M is a metal selected from Cu, Zn, Na, Mg, Ca, Ba, Fe and Sr, and n is the valence of the metal M); and (ii) providing, onto the reinforcing coating (O), a fouling control coating (X) formed by applying and curing a fouling control coating composition [x] comprising - an organopolysiloxane (AX) having two or more silanol groups or hydrolyzable groups in the molecule, and - an antifouling agent (BX); wherein the content of the pyrithione salt compound (BO) in the reinforcing coating (O) is not more than 10 wt%, wherein the reinforcing coating (O) gives reinforcement to the fouling control coating (X) and wherein the content (wt.-%) of the pyrithione salt compound (BO) in the reinforcing coating (O) is smaller than that of the antifouling agent (BX) in the fouling control coating (X). (i) forming a reinforcing coating (O) by applying and curing a reinforcing coating composition [o] comprising - an organopolysiloxane (AO) having two or more silanol groups or hydrolyzable groups in the molecule, and - a pyrithione salt compound (BO) of formula [I]: wherein R 1 each independently is H, optionally halogenated C 1-6 -alkyl, C 3-6 -cycloalkyl, C 2-6 -alkenyl, C 6 -aryl or C 1-6 -alkoxy, M is a metal selected from Cu, Zn, Na, Mg, Ca, Ba, Fe and Sr, and n is the valence of the metal M); and - an organopolysiloxane (AO) having two or more silanol groups or hydrolyzable groups in the molecule, and - a pyrithione salt compound (BO) of formula [I]: wherein R 1 each independently is H, optionally halogenated C 1-6 -alkyl, C 3-6 -cycloalkyl, C 2-6 -alkenyl, C 6 -aryl or C 1-6 -alkoxy, M is a metal selected from Cu, Zn, Na, Mg, Ca, Ba, Fe and Sr, and n is the valence of the metal M); and R 1 each independently is H, optionally halogenated C 1-6 -alkyl, C 3-6 -cycloalkyl, C 2-6 -alkenyl, C 6 -aryl or C 1-6 -alkoxy, M is a metal selected from Cu, Zn, Na, Mg, Ca, Ba, Fe and Sr, and n is the valence of the metal M); and (ii) providing, onto the reinforcing coating (O), a fouling control coating (X) formed by applying and curing a fouling control coating composition [x] comprising - an organopolysiloxane (AX) having two or more silanol groups or hydrolyzable groups in the molecule, and - an antifouling agent (BX); wherein the content of the pyrithione salt compound (BO) in the reinforcing coating (O) is not more than 10 wt%, wherein the reinforcing coating (O) gives reinforcement to the fouling control coating (X) and wherein the content (wt.-%) of the pyrithione salt compound (BO) in the reinforcing coating (O) is smaller than that of the antifouling agent (BX) in the fouling control coating (X). - an organopolysiloxane (AX) having two or more silanol groups or hydrolyzable groups in the molecule, and - an antifouling agent (BX); <EOS>