This week I've started a bit of re-wire of the boat. 

This will include fitting underwater LED lights to the back end as I am very fond of mackerel, which there are plenty of in Tasman Bay. 

My boat has an outboard pod which (by design) floods when the boat is at rest and drain when it is on the plane.

I can locate the UW lights either on the transom or on the pod.

The advantage of the pod location is that both sides of the mounting and cables holes are a wet area, so if one of the holes leaks it's no drama.  The down side is the wires will be submerged when the boat is at rest - generally a bad idea in an alloy boat.

The transom location is the opposite, the wires will stay dry(ish) up high in the bilge but a leak in a cable or mounting hole will be a proper leak into the bilge.

I can't decide which option is best.

Thoughts?

Check with your LED light supplier before installing.

I guess on an alloy boat the srcews/bolts will need to go through the transom.

Raging Bull wrote: I guess on an alloy boat the screws/bolts will need to go through the transom.

Yes - whatever surface they are mounted on they will be held in place with stainless bolts, nuts and washers (duralac to isolate from hull).

Each light needs three holes. One for the power cable and two for the bolts.  The lights in theory seal around the holes .... I'm sketical about that and I'll be using a cable gland and 3M 5200 adhesive sealant.

I ran a couple of those lights that FarmerBrowne mentions for 4 years on my last boat. One of them was still going when I sold the boat but the other had been replaced twice because water got into the lens and it stopped working. They created this really neat looking blue light around the boat but I'm not sure if it made any real difference because I only have a floodlight on my current boat and I reckon this brings just as much bait around at night, both in close and out wide. I also can't say with any confidence that the lights on my previous boat raised game fish during the day as I didn't notice any difference in that regard but I didn't have a polished ss prop either to reflect the light down into the water.

Also I recall Firmans at Napier had a stand set up in their showroom that ran these cheapie lights alongside a more expensive one (OceanLED) I think. The more expensive light was noticeably brighter from new - it was difficult to look directly at either of them. After a few months the cheapie had become noticeably dimmer with no noticeable change to the more expensive one.

So what I am suggesting is;
1. these two particular lights do not need to be immersed in water to operate.
2. The more expensive ones do last longer, although I doubt whether us rec boaties would ever stack the hours up like those display lights did so not sure if this would ever become an issue for anyone running the cheapies.