The dealer wanted $13.50 for a precut key and since I wanted 4 of them in addition to the 2 I already had (set for starting the boat, set hidden in the boat, set in the truck), I would have had to cough up $54 for four small keys. I went to a big box store and they couldn't make one. Then I went to a local locksmith and he made me 4 keys for $12. My locksmith had the correct type of blanks. Here is what he used.
http://mysecuritypro.com/yamahayh52keyblanks.aspx
The YH52 key blank is just a bit longer than my original factory keys, but they work just fine. Since they are backups it's a non issue for me.
I read on a different forum that Ace hardware carries a key that matches more closely in length. It is the SS4
http://mysecuritypro.com/SentrySS4KeyBlanks.aspx
One thing I will mention, and everyone should do this, is to write down the 3 digit key code on your keys, so that if you ever loose your original set you know that you can reorder them. Sometimes you can find originals on ebay for pretty cheap (mine wasn't available on ebay). Without that key code, you will have to call mother Yamaha with your Hull number or possibly a number off the engine to get the key number.
Here are some pictures of my YH52 spare keys.
View attachment 6042