Propeller Pockets- Benefits and Drawbacks

shallower draft is probably the main benefit. on the downside, you loose some low speed maneuvrability.

i dont' see how they'd bring more protection, most of the prop still sticks out.

As your shafts are not angled as far down you also get better top end speed and manueverability, come on plane faster and get better fuel ecconomy. All the things you'd expect from having less boat in the water. The biggest difference (and most appreciated on NJ's inland warters) though is less draft.

I agree totally with the above posters. I have also run the same hulls with pockets (after them being added) and without on production boats. The speed gain is slight but there, adding slight efficiency. You do lose some low speed maneuverability and also on a sportfish you usually tend to get a slightly less clean wash then without the pockets. Personally I feel a sportfish without pockets raises more fish, but it's unproven. Draft reduction from pockets can be a MAJOR consideration on a sportfish and greatly increases places you can go.

I agree that they don't usually offer much more protection and there is no excuse for running aground with today's modern electronics equipment in 98% of all cases

Propeller Pockets where invented by Italian Renato Sonny Levi. A pioneer in hull design and propulsion which his school of thought still bring lessons to the world today.

Advantages:

- minimizes shaft angle which increases performance
- lower draft

Disadvantages:

- higher planning speed 18 knots plus
- many tunnel prop boats also need a well placed engine and balance or else they tend to ride quite bow high and higher to the water meaning more slamming. Many English builds suffer this trend. This also means dirtier water when cruising.

When properly configured, that 'dirtier' water can be your friend...

Speaking of which, how effectively do prop pockets focus propellor thrust, which would in theory increase manoeuverability?

The same as non pockets. The advantages are shallower draft. The disadvantages are that they can slow the boat down on a really fast SF or express because it's hard to get the pockets to fill properly and you lose a little bouyancy in the stern.

What Capt J said...but if the pockets don't fill properly...you can "burn" the tips of the props especially if the clearance between the tips and the tunnel aren't precise...it's a tight rope at best. The pockets really don't provide more thrust in this situation. At displacement speeds, Kort nozzles will channel thrust. I'm telling you this jemventures because everyone else here knows this. Props in reverse lose 60-70% efficiency, than in forward gear (that's the way they were designed...to go forward) and a pocket reduces that efficiency, because the pocket narrows to the forward end, thereby restricting thrust.

I am about to order new props for my 52 Cabo Express and i have always found my blade tip to tunnel distance weird.
I have 4 inches tip to tunnel inboard and 6 inches outboard. I have read in some articles that tip to hull measurment should be 2 to 6 percent of prop diameter, my props are 34 inches....that seems very tight.
In the above pic, i see the step is added for some bubbles.
If i am going to change anything, props, add a little step like in the above pic, the time is now and was looking for others input.

That isn't a step. Hatteras yachts designed that on their boats and there are channels that go for and aft to allow air and such to bypass the prop and flow from the front of the hump to the rear.