I need a replacement boat trailer for my 21 ft center console Kenner. Need tandem axle for saltwater service. I have a McClain single axle and it's very marginal for this particular boat - rides really rough and a lot of stress on the trailer ball.

Just looking for opinions on different trailer builders.

McCLain makes a good trailer ... just want to shop a bit.

Bear

Coastline Trailers in Seadrift, TX seems to be the consensus on 2cool for best trailer for the price. We have one being built for a 21 foot Bay Stealth. Runs right at $4000 for tandem axle aluminium. I know lots of folks that have Coastline trailers under their Majeks, Haynies, etc, with no issues.

Their customer service after the sale, is very good we have heard.

We called 3 or 4 other places and Coastline was slightly cheaper or the same, and with their service reputation, we went with them.

Coastline has served me well on my current and previous boat. Don't think you can go wrong with Coastline or McClain

I got mine built by Tex-all up by Conroe. No complaints.

You did not specify aluminum or galvanized? From experience in marine business, Coastline and McClain are low cost trailers, utility grade middle of the road quality and typically under boats to get to a price point. Lodestar, Magic-Tilt and EZ-Loader are upper end trailers...,high quality.
Make sure you buy from a company that has a custom jig for your boat. You want a trailer that has fixed bunk carriers and braces that has been welded together on a jig specific for your boat model.
You get what you pay for in a boat trailer.
If you tow lots of miles don't scrimp on your trailer.

Had a McClain back in the 90's to early 00's under a Majek RFL. Frame was good. Everything bolted to it was CRAP. Inherited another McClain from my Dad when he passed with his boat. Pretty much the same.

My next trailer for this boat, or any boat I get after, will be a Coastline.

Lots of boat companies sell and deliver boats to dealers without trailers or many dealers prefer to delete the trailer from the manufacturers package so they can put a cheaper trailer under the boat to bring the price down in comparison to other dealers selling the same brand but using the manufacturers trailer.
Skeeter, Ranger, Triton, Nitro all build their own trailers and don't allow the dealers to put cheaper trailers under them.
McClain and Coastline amoungst some others build less costly trailers, so dealers buy them to package under their boat lines so they can sell them cheaper.
They use cheap import components like axles, bearings, winches, wheels, tires, untreated lumber on the bunks with single layer carpet on the bunks, etc. to hold the cost down.

We have the exact same boat, and got a Coastline out of Seadrift.

Cheap-o builders like JH Performance, Catalyst Boatworks, and Simmons Custom Boats all use Coastline trailers.

I have a Coastline trailer for my Mowdy, but its a terrible design (for my boat) and already needs quite a bit of work after 10 months. Seems like all new boats use them, but I havent been overly impressed with them.

Ram Lin, bar none, best there is, but $$$'s!

I have a McClain tandem under the Cobalt, and a Coastline under the Majek. They are the nicest 2 trailers that I have ever owned. I had to replace the winch on the McClain, but it wasn't the end of the world. Guess that it is all perspective.

I bought a new 2109 Coastline last year to replace the trailer under my 23' Explorer TV. I have no complaints thus far. The bunk supports are all welded and the torsion axles are much smoother than a conventional spring setup. I'd buy another one...

I bought a used 2003 bay boat early last year with a 2009 Magic Tilt aluminum trailer.

All in all, I've been happy with it. I'm third owner of the boat and the second owner never used the trailer so it sat in the sun outside his Tiki Island home two years. I had to replace the winch, it was only rated for ~50% of the boats empty weight, a couple other things that were likely due to lack of previous owner care. The main structure of it and the design for the boat has been great.