function validate_form() {

var theMessage = "Please complete the following: \n-----------------------------------\n";
var noErrors = theMessage

// make sure field is not blank
if (document.form1.first_name.value=="") {
theMessage = theMessage + "\n --> Your first name";
}

if (document.form1.last_name.value=="") {
theMessage = theMessage + "\n --> Your surname";
}

if (document.form1.homephone.value=="" && document.form1.Mobilephone.value=="" && document.form1.Businessphone.value=="") {
theMessage = theMessage + "\n --> A contact telephone number";
}

// validate an e-mail address
if (!/^\w+([\.-]?\w+)*@\w+([\.-]?\w+)*(\.\w{2,4})+$/.test(document.form1.email.value)){
theMessage = theMessage + "\n --> Enter a valid e-mail address";
}

if (document.form1.vessel_name.value=="") {
theMessage = theMessage + "\n --> The name of your vessel";
}

if (document.form1.LOA.value=="m") {
theMessage = theMessage + "\n --> The overall length of your vessel";
}

if (document.form1.Beam.value=="") {
theMessage = theMessage + "\n --> The beam of your vessel";
}

if (document.form1.Cradle_Hire.value=="Please Select") {
theMessage = theMessage + "\n --> Select whether you required a cradle hire";
}

if (document.form1.Drive_type.value=="Please Select") {
theMessage = theMessage + "\n --> Select the drive type of your vessel";
}

if (document.form1.Draft.value=="m") {
theMessage = theMessage + "\n --> The draft of your vessel";
}

if (document.form1.Displacement.value=="kg") {
theMessage = theMessage + "\n --> The displacement of your vessel";
}

if (document.form1.Make_Model.value=="") {
theMessage = theMessage + "\n --> The make and model of your vessel";
}

//List of dates from form for later comparison

var date1 = Date.parse(document.form1.Annual_Berth_afloat_from.value);
var date2 = Date.parse(document.form1.Annual_Berth_afloat_to.value);
var date3 = Date.parse(document.form1.Annual_Storage_Ashore_from.value);
var date4 = Date.parse(document.form1.Annual_Storage_Ashore_to.value);
var date5 = Date.parse(document.form1.Seasonal_Berth_from.value);
var date6 = Date.parse(document.form1.Seasonal_Berth_to.value);
var date7 = Date.parse(document.form1.Preferred_launch_date.value);
var date8 = Date.parse(document.form1.Preferred_lift_out_date.value);


if (date1 > date2) {
theMessage = theMessage + "\n --> You have chosen to end your Annual Berth Afloat before it begins, please select valid dates";
}

if (date3 > date4) {
theMessage = theMessage + "\n --> You have chosen to end your Annual Storage Ashore before it begins, please select valid dates";
}

if (date5 > date6) {
theMessage = theMessage + "\n --> You have chosen to end your Seasonal Berth Afloat before it begins, please select valid dates";
}

if (date7 < date8) {
theMessage = theMessage + "\n --> Your preferred launch date is before your preferred lift out date, please select valid dates";
}

// If no errors, submit the form
if (theMessage == noErrors) {
return true;

} else {

// If errors were found, show alert message
alert(theMessage);
return false;
}
}