COG Catamaran

[Newboater]

I have a question. When setting up the COG on the Genesis, do you measure the 30% of just the sponsons or 30% of the full hull from the transom to the tip? I have read this discussed on the forum both ways. I have been measuring the 30% from the full hull because I am under the impression that you should be riding on the rear sponsons only at full speed.

[CraigP]

The full hull length is what I used on mine. I agree, it’s way back to get the boat out of the water and riding on the back of the sponsons only. I can use my batts to fine adjust... Sometimes with wind or rough water conditions, you need to move them forward the keep it on the water. I have some lines in the boat to reference too, the Cat is a sensitive boat!

[Newboater]

The full hull length is what I used on mine. I agree, it’s way back to get the boat out of the water and riding on the back of the sponsons only. I can use my batts to fine adjust... Sometimes with wind or rough water conditions, you need to move them forward the keep it on the water. I have some lines in the boat to reference too, the Cat is a sensitive boat!

That is how I been setting them up also, was just curious as I have seen others mention they set them up based on the length of the sponsons.

[CraigP]

The length of the sponsons seems like a fuzzy number to me. Is it the wetted distance? The sponsons have a rise, so what do you call the reference point? It’s just a ratio, so I don’t see a problem to use overall length, which is straight forward to measure...

[Newboater]

Basically they don't include the over hang section of the hull near the transom that some catamarans have when they set the COG. For example on the Proboat Veles the sponson ends at the back of the transom. Genesis catamarans the sponsons end four inches before the back of the transom. On the genesis it makes for about about a 1.3" difference on the wet running placement. I just use the measurement as a rough starting point for battery placement before it hits the water. Yes it is basically the point where the sponson is just out of the water when running.