Block heater questions

[jmooney]

My heaters are plug in. I use them the night before we are going to use the boat . I turn them off before I start , as I have heard that the heat elements might burn out with turbulent water flow . I have no idea if this is correct. What I do know is that the aluminum heat sensor will corrode and fail dramatically, letting the coolant out . It’s good to have a working alarm system. I would check the state of the aluminum sensors at least every 5 years.

[JD5652]

Replace with 750W and put them on the HotStart thermostat. That way they cycle ON/OFF only when they need to.

My experience is that leaving them energized all the time on the thermostat has more positive aspects than negative. Also helps significantly reduce engine room condensation and rust.

[GCSI]

My boat has 3412Es, leave the block heaters on 24/7 year round.

[brico]

On my 671 NAs I have 1000W on each engine wired to the original breaker and switch them on a day ahead of starting engines from October to May here in PNW. Definitely helps starting the engine with a slight touch on the start button. This prolongs battery and starter life and I am sure helps the engine too. I do not leave it on all the time.

[Hat52MY]

We boat year round and turn them on when the temps drop below 85 and off once above 85. We leave the engine room AC lights on 24x7 which produces enough heat to take care of any humidity/condensation when above 85. This has served us well over the years.

[dar636]

Thanks everyone for the info, I've decided to first replace the 'Engine Room Outlet' breaker shown in the picture, it's not an original circuit from my delivery diagrams and I'm assuming its a 15a breaker but cannot tell until removing it. I received a new 15a breaker from Sam's which is marked as tripping at 16.75 amps. With the 2 - 1000w heater elements there'll be a 1 amp margin. If it turns out to be higher or lower rated, I'll go from there. I have a 20a breaker as well.

If that's not the solution, I am back to either replacing the 1000w elements with 750w elements, or adding another circuit to separate the L and R engine room outlets. The easiest place to start is with the breaker, sort of. The bus bar connects every breaker in the column, well see how many I have to actually remove.

Anyway, thanks for the feedback, I will update once I hit the right solution.

Dinette pic just for the heck of it.