would a 5 blade help control porpoising over a 4 blade on a 25' cat ?

Hi Dave,

Porpoising is caused by several things. The condition of the boat bottom, the ability of the prop to maintain hook up to the water, the weight distribution in the boat etc. If the problem is drive height and/or prop slip, then the five blade will help. Also, if the boat will porpoise less with more tail or bow lift, then the appropriate five blade will help. There are both bow lifting and tail lifting five blades available.

Thanks,

Thom

No matter what, 5 blades will create more stern lift than 4 blades. It is just physics. You can cause 5 blade props to have better transom leverage than other 5 blades but you can't disguise the fact that they are 5 blades.
Determining the cause of the porpoise is the first route if possible. Fix this if possible. This may be determining if you want to leverage the transom to carry the bow or if you need to lift the transom and force the boat to run flat. On a 25 Warlock, CG is key. If the boat is fast enough, the 5 blade options can be good where the air being packed is sufficient to hold the bow. Otherwise, creating bow lift will be in order or the sponsons will be so wet that speed will be sacrificed.

Brett