Power trim/ignition fuse size

I have a 1988 or 89 60HP Evinrude VRO. When I got it, I blew the fuse for the trim and ignition while on the water and had to be towed in. Found that the fuse under the cowling near the starter relay had blown. It was a SFE-4A fuse in the holder. It is about 1/2" long tiny fuse. The next time i went out, it blew again and I repaired it on the water. I found out that it tends to blow if I adjust trim while under way. I am doing some searching and see lots of people talking about a 20AMP fuse that is for the Trim/ignition. Now I am wondering if it had an incorrect Amperage fuse in there when I got the boat and it can't handle the job. My manual shows the fuse but doesn't specify amperage. Anyone have any idea? I can post a picture of the location if needed.

It is the red fuse that is circled.

That should be a 20 amp fuse !

I was hoping that. I will have to try to find a 20 amp fuse that will fit the holder. I was really worried there was some other problem with the system that I would have to troubleshoot.