@(Html.Kendo().DropDownList()
.Name("VesselId")
.OptionLabel("Please select")
.DataTextField("Name")
.DataValueField("VesselId")
.MinLength(3)
.Filter(FilterType.Contains)
.DataSource(source =>
{
    source.Custom()
    .ServerFiltering(true)
    .ServerPaging(true)
    .PageSize(80)
    .Type("aspnetmvc-ajax")
    .Transport(transport =>
    {
        transport.Read("ReadVessels", "Report");
    })
    .Schema(schema =>
    {
        schema
        .Data("Data")
        .Total("Total")
        .Errors("Errors");
    });
})
.Virtual(v => v
.ItemHeight(30)
.ValueMapper("valueMapper")
))

public ActionResult VesselsValueMapper(int[] values)
{
    var indices = new List<int>();

    if (values != null && values.Any())
    {
        var index = 0;

        foreach (var vessel in GetMapperVessels())
        {
            if (values.Contains(vessel.VesselId))
            {
                indices.Add(index);
            }
            index += 1;
        }
    }
    return Json(indices, JsonRequestBehavior.AllowGet);
}

private static IEnumerable<Vessel> GetMapperVessels()
{
    var data = new UnitOfWork();
    var vessels = data.VesselRepository.Get();
    return vessels;
}

function valueMapper(options) {
        $.ajax({
            url: "@Url.Action("VesselsValueMapper", "Report")",
            data: convertValues(options.value),
            success: function (data) {
                console.log("Value Mapper Success")
                options.success(data);
                console.log(data);
            }
        });
    }

        function convertValues(value) {
            var data = {};

            value = $.isArray(value) ? value : [value];

            for (var idx = 0; idx < value.length; idx++) {
                data["values[" + idx + "]"] = value[idx];
            }

            return data;
        }

foreach (var vessel in GetMapperVessels())
{
    if (values.Contains(vessel.VesselId))
    {
        indices.Add(index);
    }
    index += 1;
}