External Resistor?

I've got an old ebay Martinique that I've been converting into the ultimate wakeboard rig. In the mean time I feel like i'm going through external resistors faster than I should. The boat didn't have one when I got it, I put one on last year and she started to improve on start up and response. She got sluggish, and I replaced it again (the external resistor had some cracks in it) and that seems to fix the problem. She's getting sluggish again, only after about 2 months, and I noticed my external resistor is getting some cracks in it again. I checked my voltage going to the batteries, and it seems that i'm getting about normal. I am pulling a lot of weight, but I have an 11.5 pitch prop, so I thought that would fix it. Anybody have any ideas?

Dont leave the key on when the engine isnt on. This will burn it out.

How is your ballast resistor mounted? Or is it? It needs to be mounted properly to be able to dissipate the heat that is generated due to the voltage it drops. Just a thought.

Wow! Your boat has some really old equipment still. I agree with 79 - you should upgrade to a newer pointless distributor and while you're at it I'd also install a newer alternator with an internal voltage regulator. You can get a marine 100 Amp 10SI (GM type) alternator through e-bay for less than 100 bucks. I bought one for my '88 Ski Centurion (351W Indmar). It was a direct bolt on. This alternator is available in 1 wire and 3 wire hookup configurations.

If you're dead set on fixing the setup that you currently have, resistors fail for one reason- too much heat. Either the resistor is not matched to the coil or is not mounted properly so it can dissipate the heat. One other possibility is that you voltage regulator is allowing the alternator to output too much voltage. Although this will usually cause a cooked battery.

I have a brand new electronic dist and use a ballast restistor. It makes no difference on the age. You are foolish if you think that because you have a new dist that you don't need the resistor. Even if you use a conversion kit they don't say to remove it, they say check the voltage at the coil and if it reads this, then do that. Some coils have the resistor built in. SO READ THE INSTRUCTIONS, or you will go through parts that you don't need to because you don't have it connected properly.