I had new starters installed before I had the engines reinstalled in the boat 2 years ago Lol, to avoid having an issues with a starter.
I have had nothing but issues with these new starters!!
The new starters are "Arco" brand.
The first year they worked fine for a while then first the port then the starboard started clicking the solenoid. They always eventually started the engines. Not sure if its the remote solenoid one or the one on the starter itself but over the winter, I pulled them both and took them in and had the starter solenoids replaced. My understanding is sometimes they are using Chinese parts. Anyway, first time out this year they both clicked. Rap the key a dozen times or so and they would both work. Shortly after both starter motors starting struggling to rotate the engines even with both batteries. Not a typical Chevy grinding noise, just a very slow rotation of the engine then sometimes it would speed up and the engines would start. Other times I had to wait and try again. I am have a ridiculous amount of other problems so I pulled the boat and it's now back in my shop. I am pretty sure I smoked the port starter motor the last time I tried to start it so I'm going to pull them both and take them back in again. This struggling to rotate the engine is a new problem that I didn't have the first year ever. I have large battery cable everywhere so I'm pretty sure it's not that and again, this struggling problem didn't happen the first year.
I did replace one of the remote solenoids and it made no difference. Do I just have 2 bad starters??
Thanks for your help.

Wrong forum

My mistake. Thank you for pointing that out. Ill see if I can move it when I get back.

why do you say wrong forum ?

This doesn`t belong in the tech section?
General boating is not for tech questions IMOP

I get your point
but each day when i log in i simoly press on new post, wich brings them no matter where or which section they are posted... i even have to search to inow in which section they are if i wanna know it... which explains why i was not seeing the section... in my mind i was just on the oso forum.

You need to do some actual troubleshooting instead of guessing and replacing parts. I would start by removing, cleaning and reinstalling all of the ground cables. Then do the same thing with the power cables. If you still have the problem you need to take a voltmeter and see what the voltage is at every point of the circuit from the key switch to the starter.

I am betting you have some serious voltage drop somewhere along the line.

Thanks to whoever moved this thread. I am not able to because of my basic membership.
BillK, I checked over all the grounds when I reinstalled the engines last year. I didn't go over the positive side though. I have decent access to area's now after removing the exhaust so I will go over all of the connections.
I did not at the time of engine reinstallation but now am using a dielectric grease on many connections. Do you guys recommend doing that for all electrical connections?

Just had a very similar issue and it turned out to be the ground cable. All connections were good but the ground cable itself was bad and had a break in it.

I've seen battery cables that have been sitting in a small amount of bilge water get stiff and full of corrosion causing high resistance, from water getting through the insulation, cause starting issues.