Capacitors for SSB DC ground block

Hi all,

I´m planning to build a DC block for the SSB ground strap. The article
Marine Grounding Systems, http://www.sailmail.com/grounds.htm,
discusses how to make this and suggests the type of capacitor to use.
It´s the Type X7R Monolithic Ceramic capacitor, 0.15uF, 100 volt.
Unfortunately I can only obtain the 50 volt version in the place where
I am now (Whangarei, New Zealand). Are there any opinions on whether
this will also suffice? I´m transmitting using a 100W Icom 718 SSB
transceiver.

Joost Jager.
.