According to Mercury, you need the outside flaps even if you have the internal ones. Don't chance it, use the external flaps.

I forgot to say this..... I do have the external flaps on mine. I think you need to have these.

I have both sets on my scarab ! would not take a chance of having a problem because they don't look good!!!!If your boat sits as low as mine does ,nobody is going to see them any way.Swim platform covers them up most of the time......


Jim

The guys telling you to keep them on as a redundancy are correct if you lose an internal flapper, you run the risk of engine damage on start up. Have You thought about switching out the tips for a longer tip with a no burn internal flapper? Would get the spray and exhaust further away.

what if you have external flappers do you still need internal?

Well, i'm pretty much worse off than the begining of this thread.... If I have the internal flaps (in perfect shape and working order) do I acctually have to have the Outters too? It doesnt seem right to need both??

Sheer, I have had three boats with only internal flappers and no problems. My internal flappers were not like the ones in your pics. All of my tips internal flappers were and are stainless steel plates that pivot inside the tip. I am confident with these type of tips against backwash when parked or shutting down. If it was mine and I was confident that the type of flapper you have will not fail, then I would just use the internal. I still check my internal flappers on occasion to make sure they are closed when the engines are off.

If you have internal flappers, you really don't need the extrenal ones.
I have basically dry exhaust and don't have any flappers. I do have switchable external mufflers. When I dock or anchor, I just make sure to close the flaps on the mufflers.

I'm wondering if those tips come with the external flappers too? Doesn't look like it based on this....

http://www.mercuryracing.com/accesso...xhausttips.php

The previous owner of my boat gave me a set of externals too. I don't know if they came with the tips or he bought them seperate.

BTW, I had to replace one of my internal flappers and the boat doesn't have a lot of hours on it. The rubber was fine, but the metal part broke.

If you lock up a motor because of injesting water you'll kick yourself in the a$$.. you cant see them when your driving..