The messages:

<wsdl:definitions ...>

<wsdl:message name="get-tides">
   <part name="body" element="t:tideinfo"/>
</wsdl:message>

<wsdl:message name="tides">
   <part name="body" element="t:tideinfo"/>
</wsdl:message>

</wsdl:definitions>

This service uses the same element for request and response.