wave piercing bow topped with flared bow?

[Squidly-Diddly]

I still think its supposed to be a WAVE piercing feature, with the aim to be reducing the amount of spray over the ship's various equip, when the ship is forced to go at high speed in big waves while trying to use lots of radar, radio, IR, etc.

Full wave piercing is fine for WPing, if you don't mind lots of green water over the bow and rest of boat. Flared bow is good for battling big waves, but also sends big spray over boat, especially if the wind is right.

My guess is this bow represents a sweet spot. I would greatly mitigate spray problems in wide range of conditions. Only thing it might not do good is handle the biggest waves.

If its a waterline length issue, why not make the whole ship a bit longer with normal bow?

 

[Squidly-Diddly]

Actually, seems to me the bow is extended to maintain LWL. Here is a stern photo...look where the boot topping is painted. And the shafts make me shudder also.

whats wrong with shafts? Props hanging low where they'd hit bottom before rest of ship? I'd think any warship except an aircraft carrier would want something to protect the props from grounding, so the ship can be used aggressively in shallow waters without great risk of even minor grounding ending the mission and stopping the ship.
Instead of big anti-roll strakes down the widest part of the hull, have a couple of big skegs ahead of the props.

 

[Ilan Voyager]

Dear Ad Hoc, necessity is mother of invention . If Mr Marchand says himself that he added his peculiar bow design to correct a heavy nosed boat, he has the merit of being humble about the origins and not to invoke mysterious new laws of hydrodynamics. In fact his candor is refreshing. For the while his bows do the needed job, the boats are praised by the users and Mr Marchand has a easily recognizable feature to sell. Everybody recognises easily a Pentocarene design in Brittany.
His customers are happy with his designs, he is happy designing them with his assistant NA, so I'm happy for all them.
No doubt as you said the bows add waterline and volume, probably it helps to cut the waves and to maintain the characteristic almost horizontal attitude of these small hulls at speed. That must work rather well as the SNSM adopted the Pentocarene NA office design after examination of a lot of candidates as the new main rescue boat of the association, self righting all weather expected to function safely in any sea state. The guys of the SNSM are true good ones in this domain (they rescued 7700 persons in 5200 interventions in 2016 without asking one cent). With such an investment for them at 80% by private funding, and considering that the boats are expected to last 30 years, better to make the good choice.

 

[Ilan Voyager]

whats wrong with shafts? Props hanging low where they'd hit bottom before rest of ship? I'd think any warship except an aircraft carrier would want something to protect the props from grounding, so the ship can be used aggressively in shallow waters without great risk of even minor grounding ending the mission and stopping the ship.
Instead of big anti-roll strakes down the widest part of the hull, have a couple of big skegs ahead of the props.

A 140 meters 30 knots 4800 to 6000 tons patrol frigate is not expected to approach unsafely the coast at any speed and stays always in blue water, depth sonar are made for that. No hull or appendage can resist to the stress made by 6000 tons hitting a rock at even 5 knots. The last time a French frigate did such a folly at the rocky coast of the "Ile de Sein" by bad weather the armored hull had a breach of 6.5 meters and almost sank. The ship ended there its career and the captain was sacked.
But the Italian ship has a trap at the stern to launch fast intervention boats adapted to go close to the coast and even beach. For local operation very close to the coast you have specialized small patrol boats.
So the most interesting for the NA office is to optimize the propulsion which will be working 24h/7 days at very different speeds. The motorisation is very sophisticated to save fuel. So the propellers hang almost horizontal in green water far enough of the hull, so no interactions.

 

[Rurudyne]

I'd call it a semi-piercing duplex bow. I guess its supposed to pierce the small waves while retains normal bow flare as backup so the big waves don't wash the crew overboard. Looks like a retractable sonar strut instead of big over-size bulb.

This Italian navy "PPA" ship has 3 levels of power. Small motors on the gear box, diesel for cruise and GTs for speed.

A random thought: maybe those paying for the ship specified the length before she was designed, and the bow feature is there just to get the LWL the navy really wanted but wasn't allowed to have? That would have them giving a technical sounding reason for the bow, one that sounds good, absorbing the common drag reduction bulbous bow in the process.

 

[Ilan Voyager]

A random thought: maybe those paying for the ship specified the length before she was designed, and the bow feature is there just to get the LWL the navy really wanted but wasn't allowed to have? That would have them giving a technical sounding reason for the bow, one that sounds good, absorbing the common drag reduction bulbous bow in the process.

It's not a classic bulbous bow as for cargos which has a totally different shape. You can't call it bulbous bow, the shape is very far from a bulb and has far more volume.
The budget and SOR are the primordial variables. The length, which is dictated by experience of the mission or task, is within some tolerance, a few meters often dictated by the size of the available docks (you won't make a new harbor because the ship is too big for the dock...).
When you see this bow, which is far from traditional and not the simplest and cheapest to draw and to make, you think immediately that this design was surely validated at least by a careful campaign of towing tank, with a lot of considered variables. And the the results have been double checked and meticulously compared to several designs of warships of same size and task. All that preliminary hard work is cheaper than a full size mistake.
We are in warships lasting at least 30 years with a lot of constraints of design, quality and durability. It's an enormous investment, so fanciness, suppositions, and guessings are not allowed, at least in european navies. Sure and safe results are expected, there is about 80 years of experience of modern warships, so you have a solid base of comparison.
A classic bow with a ship longer of a few meters would be probably cheaper, so if they went to this bow, it's because this design has some qualities which make it superior to a classic bow at least for this ship.

 

[jehardiman]

It's not a classic bulbous bow as for cargos which has a totally different shape. You can't call it bulbous bow, the shape is very far from a bulb and has far more volume.
The budget and SOR are the primordial variables. The length, which is dictated by experience of the mission or task, is within some tolerance, a few meters often dictated by the size of the available docks (you won't make a new harbor because the ship is too big for the dock...).
When you see this bow, which is far from traditional and not the simplest and cheapest to draw and to make, you think immediately that this design was surely validated at least by a careful campaign of towing tank, with a lot of considered variables. And the the results have been double checked and meticulously compared to several designs of warships of same size and task. All that preliminary hard work is cheaper than a full size mistake.
We are in warships lasting at least 30 years with a lot of constraints of design, quality and durability. It's an enormous investment, so fanciness, suppositions, and guessings are not allowed, at least in european navies. Sure and safe results are expected, there is about 80 years of experience of modern warships, so you have a solid base of comparison.
A classic bow with a ship longer of a few meters would be probably cheaper, so if they went to this bow, it's because this design has some qualities which make it superior to a classic bow at least for this ship.

As someone who has actually designed and built government warships, the most important thing to remember is that politicians look at warships like they do hamburger...you buy them by the pound. Given how close they hit lightship to just less than 5000 tn and max displacement with full options to just at 6000 tn, I would bet that there is something in the 2014 funding provision that had those limits in it. Now given those weight limits and existing facilities, the naval architects and military sponsors try to work every trick to maximize capability within those limits. Cutting 10m off the bow above the WL is a sizable chunk of weight without significant effect on calm water max speed.