SET BIGGER VALUE IN SELECT2 DROPDOWN: SET (protected $keyType = "String";) IN MODEL 

<?php

namespace App\Entities\Mda;

use Illuminate\Database\Eloquent\Model;

class LocalVessel extends Model
{
    protected $table = "MDA.LOCAL_VESSELS";
    protected $primaryKey = "id";
    protected $keyType = "String";

    public function vessel_file()
    {
        return $this->hasOne(MediaFile::class,"ref_id","id");
    }
}