Gemini 105mc conversion Deisel to gas??

[thinwater]

Originally Posted by valhalla360

People are missing the point. The problem with inboard gas engines on monohulls is any leak or fumes from the tank or engine wind up in the bilge where they have no way to escape, so you can have a risk of them catching fire. Hence the need for blowers and sniffers.

On a Gemini the gas tanks are in the bridge deck with vents on the bottom that lead under the bridge deck (not into the hulls), so any leaks or fumes DO DRAIN TO THE OCEAN. Furthermore with an outboard, if there are any leaks at the motor, those also drain to the ocean.

It's an apples and oranges comparison.

Exactly. This is how all gas powered cats are built. Tanks on the bridge deck in sealed compartments, drain and vents out the bottom.

The biggest problem I see is that the engine is now far aft and will pitch in waves (the PDQ engines are 10' farther forward).

[Lizzyfish]

That is a simple conversion and a good move.

[Bean Counter]

Just curious, what is the alternator 12 Volt / AMP output of the diesel compared to proposed outboard. Also does the diesel heat the water?

[valhalla360]

Originally Posted by Bean Counter

Couple of items here.

1. A Gemini factory built with a diesel engine, does it's fuel tank vent and have same safety systems as a gasoline designed one?

2. The point re the dinghy was sailjumanji post asking if the dinghy ran on gas, then implied that if you carry gas for the dinghy why comment that having gas on board was unsafe. I would suggest the same in your outboard powered Gemini if you carried spare gas below decks, or in a non draining un-vented storage locker.

.

1. The single diesel gemini gas tanks are identical. No gas sniffer or blower with or without gas as the spaces drain overboard.

2. We had the jug for dingy gas tied off between the davits on the back deck outside the cockpit. We could also transfer to the main ship gas tanks with a simple siphon. There is a ridge approx 1' high separating the back deck from the cockpit so any spills would again go overboard (though with the siphon it's not an issue)

[valhalla360]

Originally Posted by Bean Counter

Just curious, what is the alternator 12 Volt / AMP output of the diesel compared to proposed outboard. Also does the diesel heat the water?

Depends on the outboard but 7-10amps. On the plus side we could easily pull start the motor, so a dead battery isn't a big issue. Solar panels were our primary means of charging. We didn't even have a shore power charger, so never felt the need for more.

You could modify the diesel to heat water. This is probably the biggest advantage to the diesel but easily balanced with the extra cost and maintenance for the outdrive.

[captstu]

Shearwater and Grouchy Turtle were both solar powered and lived off grid. Both used propane instant on hot water for all needed hot water. Both had larger than original 12 volt fridge/freezer.

[catsketcher]

As to the OPs question, I haven't but I thought of going the diesel and went single outboard - it worked well for 17 years.

We had a single Yammie 25 and it is a great outboard - lovely big prop and lots of low down grunt, especially in reverse. I have had the Yammie 10 years and it has been a dream engine.

I would not like to have the jack plate on my cat. The one shown would be terrible to my sensibilities. It looks like it would drag in the water a lot and slap on almost any chop, even with the jack plate up. I love sailing with no underparts banging, banging makes me less happy so Kankama almost never bangs.

I made a pivoting nacelle that gets the outboard well down when required and fully up when sailing. I installed it two months ago and it is great, getting the motors (I have two now) up nice and high unless motoring. You can build one yourself out of plywood and epoxy. It doesn't take too long. It weighs less than 25kg. Better than the jack plate version and much cheaper. You need a 4:1 to lift the 25 easily. I don't have photos but the CAD drawings may help.

[valhalla360]

Apparently never took a picture really focusing on the bucket but this one shows it a bit.

Some more pictures of the underbody here:
https://valhalla433.wordpress.com/about-valhalla-ii/

[Factor]

Yamaha dont make a Gas engine. They however make a petrol one.

[44'cruisingcat]

The vast majority of powered boats are trailer boats with outboard motors. Being outboard powered certainly doesn't have any negative impact on their resale value. Quite the opposite. Inboard stern drives are generally seen as a liability.

[catsketcher]

In the very small sample size of my catamaran friends and acquaintances there are different attitudes towards outboards.

In Tassie the locals tend to like their diesels, and two cats have been changed to diesels. But Tassie can be a wild place to sail and they don't often put their boats on the sand to dry out.

My Queensland and NSW friends are different. One bought a Tassie boat and thinks about turfing the diesels and installing outboards. Friends with diesels with a larger than their previous cat, ruefully reflect on the hassle free nature of outboard ownership compared with work on props, filters and hoses.

There will be some people who like diesels and some who like outboards. There is no one way street of buyer intention. Until I went to Tassie, almost all people who could wanted outboards. As to the selling potential of outboards due to their volatile fuel, it would only make sense to ditch a petrol cat if you ran the stove on Kerosene, as the gas stove should be much more of a concern.

I would vote for the Yammie 25 and easy motoring.

cheers

Phil

[Drmanso]

How about installing 2 Outboards such as the 9.9 Yamahas?
The redundant power should be more reliable than a single diesel, they will weigh less also and will enhance the maneuverability and resale value.
I'm about to buy a cat and really like the Gems, but Im leaning toward a PDQ 36 because it has 2 outboards.

[captstu]

Different boats. Twin 9.9s are fine. I had one 15, the Boat turned on her own length easily. I question if 2 engines give you anything beyond twice the maintenance. My Merc 15 never had any problems except bad fuel, once. If I were doing it again, I’d get a 3200 and add two sugar scoops, each with a 9.9.

[ohdrinkboy]

At the 2017 Annapolis Boat Show, I mentioned to the sales rep that I would rather have 2 outboards instead of twin diesels. He said it is now an option.

The old MC should have been designed for ouboards in the hulls as an option.

[Boosted]

Originally Posted by ohdrinkboy

At the 2017 Annapolis Boat Show, I mentioned to the sales rep that I would rather have 2 outboards instead of twin diesels. He said it is now an option.

The old MC should have been designed for ouboards in the hulls as an option.

Oh, cool! I haven’t spotted a new outboard production Gemini. I’ll keep an eye out as I’m interested in seeing how it’s setup.