Interceptor plates on pockets/tunnels?

Band-aid for miscalculation on the original build, or to compensate for added weight at the stern following the addition/extension of a swim platform or to counteract interference, etc.

Static interceptor to provide lift in the stern and unless its electrically or hydraulically articulating, you can't tell from the photo it would add variable trim.

I'm no hydrodynamicist by any means but it would make sense the more trailing edge wet surface area involved (i.e. keel) with the interceptor would provide more lift? Maybe our resident past life hydrodynamicist will chime in for input.

It is made for shock absorbing and easy replacement like a car bumper.
new sunseeker 95,same style bow have

On page 2 of "Review: McKinna Yachts 70' Pilothouse Motoryacht" there is something similar to that plate, not sure it is what you are referring to.

The placement of these plates around the prop pockets would be an effective way to induce positive trim via thrust. It should be specifically useful coming on plane where traditional interceptors are not because they are typically mounted outboard of the thrust line, closer to the chines to control roll.

I agree Pascal. The vertical sections appear to create more drag than lift, but it's the sum of the surface area that is contributing to an encapsulating effect. The vertical sections aren't just redirecting flow, they're diverting thrust which adds lift coming on plane.

I have that underwater stern piece on my inflatable SUP, it aids in water release of the back. This sanlorenzo stern fixed vertical piece must be an after thought related to water flow. Nicely propspeeded to boot!
Keep ‘‘em coming @Pascal

Those additions are made like 1 inch down the hull horizontal line, and I think they are made to keep the bow down. They look after market IMO.

I have not seen any SL with them, though I have not seen many of the new ones.
This Sanlorenzo looks an SL102A.

There might have been somethings going on here, may be, and stabilization (most probably fins), which made the boat run bow high at a certain speed and captain decided to intervene.
Remember when you have fin stabilizers open your trim tabs or blade style Interceptors become useless, and even closed they lose efficiency.

As for the bow section there also a mistype in some rules, and while standard YM licence can helm you up to 23.99 m on load-line-waterline length (UK flags etc) some other flags will want 24 m hull length (Italian / French flag for example).

I can’t believe I was correct on the interceptor plate.
It breaks the flow to release the hull and enhance flow. Just like on my Starboard inflatable S.U.P. Paddle board designers are all about getting hulls to flow through the water.

@ JFM , how did it feel in a test drive ? Assuming you had a ride before pulling the trigger ? Did you notice any unusual stern sinking or bow rise anywhere.Was thinking the transition from D speed to P speed ?

Secondarily had it got a extra large below deck in particular the owners mid cabin space ? Thinking they have pushed the machinery space as far aft as they can get away with for the benefit of interior vol ?

Compared with near or direct competition.

Stern sinking/bow rise? Transition? On a 30m/110 tons boat? Seriously?
I'm looking forward to reading the reply...

Hold on put the safety on and holster your weapon sir !

If the permanent bolted on semi adjustable “interceptor “works then the answer should be a NO . Otherwise what’s it’s raison d etre ?

Prop tunnels kill stern lift a major disadvantage, but countered by the lower shaft angles achieved a arguably better advantage in this case .Again erring on the side of rearwards machinery packaging gaining more interior volume .

The time you are gonna need max stern lift is in transitioning, or turned around notice an issue , bit lacking ..of course just temporarily .

On the plane all trimmed out running along due to the speed the whole hull of this length and weight will , or should I hope sit balanced pretty flat .That’s why I enquired about the transition phase .
By not mentioning “ transitioning the stern sinking / bow rising” etc are you indirectly inferring the permanent interceptor illustrated in the pics ^^ are needed to get the thing to run level at planning speeds , ie without them it runs bow high ?

I think they are there to increase the already refined transition to bring it up to a even better level ( scuse the pun ) …..in a complementary way exceed expectations.That’s why I asked / enquired .

I just can’t see them ( San Lorenzo) cocking up the hull calcs like other posters , Unless JFM reports different?

Unless some one can think of any other reason for the permanent interceptors ? They ain’t there to look pretty in the yard or snorkelling are they ??

Fiammetta, as mapism says there is absolutely no transition in a 96 ft / 100+ tonnes boat. World of difference from 6 tonnes/40 feet.

this sanlorenzo doesn’t even fully plane- hull supported by buoyancy, as much as by waterskiing on the water surface.

There are a few running shots in this video. Not incredibly fast- maybe 15-17 knots. Her ride looks good to me. That’s Ace’s boat- he sometimes posts on here.


By the way, mine is pretty custom and will have the largest ever engines in an SL96A, so I’ll report back.

That SL interceptor edge sticks down only around 3/4 inch so there is no way it is trying to make lift, in the same way a Humphree interceptor or classic trim tab does. It can only be to create a cleaner and more constant point where the laminar flow separation occurs, like a lip spoiler on the trunk lid of a fast saloon car (which is not there to create downforce and is only there to define and keep constant the point where laminar flow separates).

This boat’s GA is a compromise like them all. Engine room is tight, to make big accommodation and an especially big garage. It’s just a choice/trade off that a customer must choose/make. I would buy the SL 106 instantly if it weren’t for the regulatory rules that I’d then have to endure. Compromises compromises!

You know, as far as I can tell from the photos, I wouldn't actually call those design completely different.
OK, your "office" doesn't have trim tabs (and neither a stern thruster, as far as I can tell), but these are just accessories, so to speak.
Both very common - and often standard at this size, in fact - among EU builders, but I'm willing to bet that also in the SL the trim tabs aren't strictly necessary, and they are more meant for fine tuning than anything else. Besides, there's no such thing as a twin props boat that really needs a stern thruster of course, it's just an additional convenience, possibly triggered also by the fact that mooring stern to is rather the norm than the exception, in the Med. The basic design is instead pretty similar: both are shallow vee hulls with prop tunnels - unsurprisingly, for boats of that type/size.

Imho, the only difference worth mentioning is that the Lazzara gives the impression to have been built extending an existing, slightly shorter hull.
And I'm guessing this for two reasons:
First, there is no reason why the part that you highlighted in red shouldn't have a proper hull underneath, making the "real" boat hull 3 feet or so longer without affecting the overall boat length. The hydraulic platform is overhanging anyway, and in fact, as you can see from your own photo, the SL hull goes all the way astern, up to where it's necessary to leave a void space for lowering the swim platform.
Second, the props and rudders are significantly more forward (another 2 to 3 feet, possibly?) than they could theoretically be, still remaining inside the existing hull. And this is a trick used by many builders for making an existing hull longer without redesigning the whole powerplant placement (hence the hull mould), in order to shift the props and rudders as astern as possible, as is normal when a completely new hull is still on the drawing board.
I'm not familiar at all with Lazzara, did they build a 110' or so model preceding the 116', possibly?