Now this is a suggestion. If you do not know of the Manila Galleons here:

The Manila Galleon (Spanish: Galeón de Manila, Tagalog: Kalakalang Galyon ng Maynila at Acapulco) were Spanish trading ships that sailed once or twice per year across the Pacific Ocean between Manila in Spanish East Indies (present day-Philippines), and Acapulco, New Spain (present-day Mexico). The name changed reflecting the city that the ship was sailing from.[1] The trade route was inaugurated in 1565 with the discovery of the ocean passage by Andrés de Urdaneta, and continued until 1815 when the Mexican War of Independence put a permanent stop to the galleon trade route.

I would like this ship to be implemented, the info (building supplies such as wood etc, armament, cost both turns and gold)

Cost- 714,285(regular) 607,143(When 15% bonus is applied) 500,000(When 30% bonus is applied)
Turns-120 (suggest differently if you feel)
Wood-1200
Iron-800
Tools-360
Cotton-220
Cannons/Armament- 45 or 50
Crew- 225 or 250
Cargo- 150-175(suggest differently if you feel)
Speed- Half the speed of Flag Galleon, (feel free to suggest different)
I will have an image soon, unless someone else has one.

The usual question is, how will this ship affect or interfere with the current major trade ships trade galleons and large merchantmen. In other words, how will act on the playground? Will the others be ignored?

Due to it's speed, cost to build, as well as supplies it cost to build it, I would say that it would Keep the others the preferred one to build. The others are faster, cost less, and require less materials to build.

In my opinion i would put one of these in all my trade routes, as to not slow them down to much, but still have the power of this ship in the fleet.

base speed of a flag galleon is 0.8815 ( i think it got faster or got more cargo recently cant remember although that number is kinda old so it may be wrong while the lmm base speed is 0.96 so the manila would be 0.44 big difference it can be used for close ports so i think it wont affect the other trading ships

So what makes this ship more preferable than the usual escorts for trade fleets, the flag galleon?
BTW, I'm just asking these questions to get you to push on why this ship is good and to get more explanation. Some of these questions I can assume an answer but it is best if others don't have to.

What makes this ship more preferable over the Flag Galleon as an escort ship is:
1. It's cargo capacity, the fact that it ties the Trade Galleon for largest cargo is a good thing for any fleet, meaning it won't lower any fleets total cargo and in some cases improve them, however slightly.
2.It's armament, with it having(if put in) the 3rd largest in the game making it a formidable ship to battle, when it goes up against any of the average raiding vessels.

The things that keep other trade ships preferred over this ship are:
1.It's speed, it is now (i think) one of the slowest ships in the game, it's speed by me was not chosen to make it be considered, but because in history an average Galleon weighed around 500tons, while the Manila weighed 2,000 tons, obviously slowing it down.
2. It's much more costly to run. I don't know the exact numbers but for this ship to be a much more effective trade ship it would have to be running with full crew, and to serve it's escort roll, full cannons. Making it much harder to turn a profit with a fleet of five of them running just for trade. Keeping the Trade Galleon and the Large Merchantman the preferred trade ship.