I picked up a martin "20" at an estate sale mainly because i like messing around with the old time outboards but i have never heard of or ever seen a martin motor before. can someone tell me the hp of it and the approx. year. I had a couple peaople offer me alot more than i payed which makes me wonder what i have anyone with any info would be greatly appreciated. thanks alot. whats it worth and is it rare?