Forgive me for taking some time to respond to this but there is a lot to unpack here.
How do Ships Fight?
The first thing I will say is that the worst possible place you could be if you are a Ship is alongside.... Why? Because Ships defend themselves with Manoeuvre as their first defence. Only through Manoeuvre is a Ship able to make appropriate use of all of it's Non-Kinetic and Kinetic Effects. The response or action the Ship will take is dependent on the type of threat: Air, Surface, Sub-Surface, etc. When we talk about Surface and Air threats and how Ship's deal with them specifically, what you are describing is what we call Detect to Engage Sequence. The Detect to Engage Sequence describes the process by which contacts are identified, warned and if necessary, prosecuted.
The purpose of the Detect to Engage Sequence is to be able to make an early detection and classification of incoming threats and be able to effectively use the appropriate weapon to engage and defend the Ship. Detect to Engage occurs in 5 Phases, they are:
Detect
Localize
Classify
Track
Engage
These all occur at different ranges from far to near and dependent on where the threat is will influence what system is used. I can't get in to specifics on this for obvious reasons but in order to effectively defend itself a Ship needs to be able to Manoeuvre. The reason for this is that the best way to actually defend a Ship from aircraft and missiles is with Soft Kill Systems AKA Chaff, Jamming, etc. Effectively using the Ship's Soft Kill systems requires you to be able to manoeuvre. If we are talking about Sub-surface threats, manoeuvre and counter-measures are the only Defence you actually have.
Why Ships Must Avoid Littorals and Areas that Restrict Manoeuvre?
As far as fighting in the Littorals is concerned, Ship's are at their biggest disadvantage in Littoral waters because it limits their ability to manoeuvre, which limits the ability to bring all their weapons systems to bear and also constrains their ability to actually Mass combat power. Mass is one of two critical elements of Naval Combat and is a key predicator of success. The other is Scouting, which I will get in to later.
On the water, everything is open, there is nowhere to hide. If you can see the enemy, he can also see you. This is even more prevalent with modern sensors which can detect threats long before a Ship is even in a position to actually effectively engage in a way that guarantees a successful hit. So how do you gain an advantage? With numbers of course. Mass is critical in Naval Combat and it's basically a case of whoever is able to bring the most guns, missiles, torpedoes, etc to the battle wins. Because Ships are not able to make use of terrain or other features in the defence, it makes no sense to piece meal forces. When Fleets do actually fight, the best way to guarantee success or at the very least, prevent defeat in detail, is through concentration of force/firepower.
It was shown over and over again in the Pacific Theatre in WWII that dispersion and piece-mealing of Naval Forces was a surefire way to lose a Naval Battle. Why? For one thing, Ship's are a lot harder to sink than we actually think they are. Secondly, Fleets were being detected well before they ever got the first shot off and Defence is at a huge advantage in Naval Warfare. Most of the offensive combat power in a Naval Force is actually contained in the Aircraft Carrier or other Capital Ships. Finding the Carrier was relatively easy, actually getting planes to it was rather hard. If you showed up to a battle with 1 Carrier and the enemy had 2, it was basically a guarantee that no matter what you did, the enemy fleet would win simply due to math being on their side. The Carriers would have enough warning from their screening forces of an impending attack that they would be able to get their aircraft in the air and even if you launched the first shot, they would be able to successfully defend themselves and then counter-attack at which point, the math and statistics take over and your forces are attrited at exponentially every successive attack.
There is no cover or concealment on the water. If I have 20 guns and you have 10 guns (A 2:1 Advantage) and you point and shoot at 10 targets and in the unlikely event score 10 perfect hits, I still have 10 untouched guns left to return fire with. Now lets be more realistic and say that only 50% of hits were effective. You shoot your 10 which is really only 5. I now have 15 left and shoot my 15 which is really 7 or 8 if I round up, you now have 3 and I have 15 left..... I think you get the drift.
I've put it in a table for you to illustrate the effect of concentration of force:
Combat Power = 50% effective Hits | Attacking Force (AF) (1:2 ratio) | Defending Force (DF) (2:1 ratio) |
---|
Start of Battle | 10 | 20 |
AF Attack | 10 | 15 |
DF Counter Attack | 2 | 15 |
AF Counter Attack | 2 | 14 |
DF Counter Attack | 0 | 14 |
Likewise, if the Attacker has a numerical advantage at the commencement of the Battle, the advantage is even more pronounced:
Combat Power = 50% effective Hits | Attacking Force (AF) (2:1 ratio) | Defending Force (1:2) ratio) |
---|
Start of Battle | 20 | 10 |
AF Attack | 20 | 0 |
DF Counter Attack | 0 | 10 |
KevinB's example of the Navy being like the Borg is apt. Dispersion on the water = death. If you disperse, you're inviting your fleet to be destroyed in detail. So if you can't disperse how do you gain an advantage? The answer is Scouting.
Scouting is a Critical Component of Naval Warfare
Arleigh Bruke is famous for the following line: "The difference between a good officer and a poor one, is about ten seconds." What he meant by this is all things being equal, whoever takes the first shot wins. This is why finding the enemy before he finds you, is of critical importance in Naval Warfare.
Scouting in Naval Warfare is the only way to give you any sort of advantage over your adversary. All things being equally, localizing and finding your enemy is the only thing that is really going to give you an advantage in a Naval Engagement. This is why Fleets fight the way they do with various layers of defence and detection, the most deadly ones being submarines.
Why do you think that every Navy in the World (except us it seems) is aggressively pursuing submarine and sub-surface capabilities? It's because with the proliferation of satellites, long-range aircraft, unmanned aerial vehicles, cyber technology, etc. The only real place on the water that a Military Force can actually remain undetected is under the water. Given the advanced detection capabilities that modern Navies have at their disposal, everyone basically knows where each others surface ships are at all times. This further erodes the argument that one should disperse ones Naval Forces.
Given this fact, concentration of force is even more critical today than it was in Arleigh Burke's time. Scouting is also critical and Canada is making a huge mistake not seriously pursuing a real submarine capability which is the only way we are going to gain any sort of advantage over our adversaries in an actual shooting war.
So What is the SO WHAT of the Above as it Relates to What You Wrote?
Your idea that we should tie up a Frigate alongside somewhere and use it to support land forces would be a misuse of that asset. Blue-Water Ships are at a huge disadvantage in littoral and constrained waters. They are unable to make full use of their kinetic and non-kinetic sensors and weapons and are at a huge disadvantage against both symmetric and asymmetric threats in that environment. The old adage, "A ship's a fool to fight a fort" comes to mind.
If the Canadian Navy wanted to consider getting serious about operations in littorals, it would invest in submarines, marine commando forces, commando support ships, unmanned systems, etc. Likewise, you would never conduct an amphibious invasion through littoral waters, you would do it from the open ocean with your amphibious forces remaining well offshore until the conditons had been set for them to proceed inland.