Do Outboards Make Sense on a Performance Cruising Catamaran?

I went over this same decision when I was looking at getting a Seawind. In the end I spoke to someone who's got the Yamaha outboards on his Seawind and he's really happy with them. He's based in Singapore and has sailed all over SE Asia in his boat and he's happy with the Yamahas since he can get parts and service nearly anywhere. He also has a Honda portable Gen set he uses and has only one type of fuel on board. He carries extra fuel for his outboards, generator and dinghy and often runs on one engine to extend range. He loves pulling the engines out of the water to reduce drag during sailing and he's always getting caught in fishing nets etc so pulling the props out and removing the stuff stuck to his props makes things easier. However, if he was living on the boat full time he'd get diesels. He only sails a few weeks at a time so the outboards work better for him in that situation.

Diesels, for sure. Can't beat the fuel efficiency and increased range for travel. Your going to appreciate the tremendous amount of amps they can generate to charge your lithium battery bank.

Thanks for the update. Diesels over outboard is the traditional response and I would agree wholeheartedly. To be honest, any inboard configuration ( even gas or electric) would be my preference over outboards. I think the better discussion is the relative merits of sail-drive vs a straight propeller shaft.

The diesel would be my choice regardless of cost because of the charging capability and the extra torque or thrust. If you ever get into a tidal change with 6 knot currents and high winds the diesel pays for its self. That is an extreme but I have found it prudent to always plan for the worst. If cost is the final factor Then the outboards will work fine because I know you plan based on their capabilities. The big factor here is that you do get to make the choice. The new boat is coming.

I wish I had known you were asking for input on outboards- we chose the outboards. We have found that the diesels run a knot slower under sail because of the drag/ weight. We have a diesel generator and outboard motors. We will be using the "inboard" space to hold our scuba equipment. We are also live-aboard, though we are coastal cruisers. Regardless of the engine, we recommend running only one unless necessary- it doesn't slow you down and you save so much fuel! (AND WELCOME TO THE SEAWIND FAMILY!!)

I would go diesel ! I have a Wharram cat with two Y 9.9 outboards… I am constantly cleaning carbs and desalting from sea spay up into the outboard sleds. The weak link in my vessel for sure.. congrats!!

After watching so many cruisers doing engine compartment yoga while sweating their balls off I feel like this category should carry additional weight under the quality of life category. Even the hassle of maintaining a folding prop verses an outboard prop is a big difference, not to mention the expense. A folding prop means carrying more spare parts, greases, zincs and prop coat too. When you're in crocodile water out in the middle of nowhere working on your prop while trying to not lose your tools and parts to Neptune your value scales tend to shift. I've been on the fence for what I would actually choose but can I say that I feel like I'd prefer a third option? It might be cool to have a decent sized gen set that is accessable for maintenance and two electric outboards. That way you eliminate most of the negatives of outboards while keeping most of the positives. If the Genset takes a dump on you then you're still in better shape than a monohull because you maintain some redundancy because the solar will provide electricity to run the electric outboards. Not enough to motor out of a no wind situation but enough to get in and out of an anchorage and set the hook. Aircon would be a nice bonus under this setup too. I know it isn't a perfect solution but I like the pro's vs con's a lot better. As a general philosophy I feel like the best part is no part. The less complex something is the better. Less holes in the boat for props and raw water is better. Less internal combustion engines to maintain is better. Less prop complexity, maintenance and parts is better. Unless a person enjoys engine compartment yoga, trying to get all kinds of parts while in the middle of nowhere, extra work during haul out, and spending tons of money.

Something you did not hit on is hull penetration for prop shafts. I have an I/O drive on my gas driven boat and I have had water leakage due to the shift cable boot. I completely understand your well thought out choice for inboard diesel. With outboards you have no potential leak points.

Good choice. I was part of a crew that moved an older Seawind from the west coast of Florida to the Miami boat show and back. Pushing into the wind going across Florida bay the outboards cavitation was a huge issue. The fuel fills where on the bridge deck and the vents were sketchy so we had to close up the hulls when fueling. The range was so poor we had ten Jerry cans lashed to the stern (which expanded in the sun and dripped )

I've had inboards and outboards over the years. I found that lifting my outboards out of the water when idle prevented the galvanic corrosion I experienced with drives that sat forever in the water.

I like having 3 identical motors. I lived on my own in the bush in BC and Nova Scotia/New Brunswich. Budget is key, but layers of protection are key as well.

We own a PDQ cat and I just changed out my two Yamaha 9.9 high thrust motors. The old ones lasted 17 years. We also run a 9.9 on our dinghy so can share spare parts mostly. Can’t beat the replacement cost! I would probably prefer diesels but I’m quite happy with my outboards! It would be nice to have more power generation however.

Good choice :-) I would have done the same, the most important pros for me would be 1. Range 2. Electricity production 3. Noise

You made the right choice. Most items/options, you can add later, after you're sailing. The diesels obviously need to be part of the initial build. So ya, good choice! Good luck with the sail drives. Obviously a straight shaft would be simpler and more robust, but it is what it is. Hopefully they will be trouble free or as trouble free as sail boat stuff can be. 😀

I have a 24' catamaran. Originally, the outboard was slung over the back beam, on a swing arm to go the more than 2' down to the water. This combo was too heavy that far back, even with the 4hp 2 stroke engine. So much cavitation too. I moved location to under the centre of the bridge deck and mounted the new 9.9hp 4 stroke in a nacelle made from the front half of a Dart 18 racing cat hull, which hangs one foot clear of the water. No slaming. Cavitation only happens in steep chop. Obviously this was a weighty addition. But having replaced the165kg 'one piece' fibreglass bridge deck/back beam with foam core deck and aluminium truss back beam, I've actually saved weight! Pitching is less too. Happy days.

Have to wonder how many of the commenters have or do own a Seawind. I have owned a Seawind since 2012 and would point out they are designed from the ground up for outboards. Outboards with a long shaft and high thrust options. Mine has 12 inch elephant ear props. I have never had an issue driving the boat against current and wind with this set up. The placement of the outboards is well forward and the boat turns in it's own boat length 180 degrees. This is because the outboards are much farther forward than the saildrive is. Not only does the forward position aid in controlling the boat it also helps with cavitation. The biggest factor for me is what I will call sailing style. I looked at some of the peeps who have commented and they seem to have what I call condomarans which are often dissed because they motor so much. On the other hand on one three month cruise I would up using less than five gallons of gas in large part because I only used the outboards when anchoring to back down. Sure I was limited by the wind speed and direction in my choice of when I could make a passage. But as my Dad use to say 'a man in a hurry has no business with a sailboat'. For me it is a no brainer that outboards are a better choice. The huge advantage in being able to crabclaw the boat sideways to dock and the additional speed when sailing because the outboards are out of the water as well as no need for zincs because no metal is in the water (I have a composting head so no through hulls) far out weigh any fuel savings of a diesel; not to mention a huge cost savings.

Don't forget about grounding with the sail drive legs. The outboards will kick up in the event of grounding. I personally like the outboard option with lighter weight better sailing and the ability to carry more personal gear for cruising. Add a few solar panels to make up for the power needs.

What a roller coaster conversation!! It made me kinda of freak thinking about u getting the out boards. Once u said noise I was sold on the diesel!!

In my view, for liveaboard, adventuring, anchoring out sailors, the inboard has many advantages to offer. Not the least is hot water production for showering and dish rinsing, in addition to the electrical contribution, noise reduction, and range advantage, with a less volatile fuel.

Bummer on the build delay! Our world is so screwed up with the Covid, you just have to learn patience! So glad you have decided on the Diesel engines. Your explanation of the options just helped you make this very important choice and, in the long run, should pay out Big time, especially if/when you sell. Loved your ending “out takes”! It shows how you kids are real and do disagree sometimes. Remind us every once in awhile any wedding plan ideas. We are so looking forward to that event!