1981 Montauk 17 Battery Installation

[Boatshop6581]

I am planning to relocate the starting battery from the aft port side deck area to the forward inside of the center console during the repower of [my 1981 MONTAUK 17] boat.

I am also thinking of putting a second deep cycle battery inside the console for the trolling motor.

These modifications will require fabrication of longer battery cables. Tbe batteries will be Group 24 case size.

Q1: is the console floor strong enough to handle the added weight?

Assume the batteries are centered and properly fastened down in battery trays.

[ConB]

What some folks do, myself included is cut the floor of the console so the battery box goes through the floor and rests on the deck below. I also put a block of wood under the floor down to the deck to help support the floor.

Con

[Boatshop6581]

Thanks for the info. I am thinking that I'll put a support under the floor of the console, rather than cutting out the floor.

The sides of my console are sitting on what appears to be aluminum angle brackets, and there are stainless screws and washers through a strip of teak approximately 1-1/2-inch high and about 3/4-inch thick, that sits on the angle bracket.

I don’t know what holds the metal angle brackets to the deck.

Q2: is this the OEM rigging?

If I coild lift the console a bit then I could install some support structure underneath. Otherwise, I'll have to wedge a piece of wood or board or something under the console floor for a temporary strut.

[jimh]

Q1: is the console floor strong enough to handle the added weight [of two Group 24 lead-acid storage batteries]?

A1: The floor of the console is not designed to hold two heavy batteries.

Q2: is this the OEM rigging?

A2: The method of fastening the console to the deck you describe sounds like the OEM method.

[Boatshop6581]

Thanks to all. Time to start some re-engineering. Looks like I have a couple of options. Either the batteries will need to be mounted to the deck below, or I will need to create a support structure underneath the console. Good to know that the mounting configuration appears to be original. I appreciate the inputs.

[jimh]

The weight of the trolling motor batteries could be significantly reduced by using Lithium-Iron-Phosphate (LiFePO4) batteries.

The cost of marine grade LiFePO4 batteries has decreased in the past three years to be not very much more than extremely high-quality, sealed, valve-regulated, absorbed glass mat (AGM), ultra-high-purity, lead-acid batteries, whose cost has been increasing.

Consider using a cooler mounted forward of the console to house the battery or batteries for an electric trolling motor.

When planning for new replacement cables to the engine from the engine starting battery, you can use the Ampere-Feet method to select the appropriate wire gauge for the new cables. See

Ampere-Feet
https://continuouswave.com/whaler/refer ... tion1.html

Trying to re-use the original cables by adding extension cables is never a good approach.

[MarkCz]

You can make an adjustable thickness support out of a 4 x 4 cut into wedge shapes like a giant pair of door stoppers. The individual pieces will fit in the lower kick space and if you then align and stack them you can slide their inclined-plane faces together; the thickness will increase and you can get a snug fit supporting the console floor. I would add a few stainless screws through the console shelf floor and into the wedges to lock them in place so they don't shift.

[Boatshop6581]

That is an ingenious solution. Elegantly simple and effective. I'll see if I can find a good woodworker to cut some pieces to the correct shape. I have lots of tools but not any good woodworking equipment. A nice big bandsaw would help. In the meantime, I am fashioning an adjustable 'jackscrew' with stainless hardware and a block of pressure treated wood as a 'foot' so I can operate the boat in the interim. I have recently relocated to a new area and have to find a local cabinet maker to get access to some good pieces of hardwood.

Thank you for the suggestion.

[Boatshop6581]

Thanks for the info on the batteries. When the current ones wear out I'll probably replace them with the more modern ones that you mention. In the meantime, the console floor is getting supported to handle to load.

In regard to the wiring - yes, the size of the cables has been adjusted to account for the increased length. I just re-powered to boat with a new Yamaha 70, and the dealer who installed it rigged up the cables to the appropriate size. The same with the trolling motor and we installed a circuit breaker on that as well, to provide protection on that wiring run.

[Phil T]

When relocated the battery on my 1987 Montauk 17, I ran AWG-2 marine battery wire from the engine to the console and a new OFF-ON battery switch. I recall it was about15 or 17 feet of wire.

To do it again, I would go with 4-AWG wire. Use of 2-AWG wire was excessive.

Cut the floor and have the battery box sit on the deck. Some install a square or two of dri-dek to allow water to pass underneath.

[jimh]

NOTE: Unrelated comments about boat speed performance have been moved to the PERFORMANCE forum in a new thread on the new topic.