I had a marina where I rented several houseboats both with I/O's and outboards. Hands down the outboards where easier to maintain and the cost to repair was generally less since I didn't have to pull the boat. Fuel consumption was about the same - a little higher with the outboards. Handling was better with the I/O's, more low end torque than the outboards. If the engines are used like the average boater uses they might get 25 - 50 hrs of actual run time a season ( a two stroke engine will get about 400 to 700 hours and four stroke 1000 to 1500 hours before a major rebuild. The Honda four strokers should hold up 20 years if maintained well at this level of use, I had very good experience with them. If the installation is done nicely I think you should end up with a useable boat. A key issue with an outboard is the proper size prop- choose the wrong one and you'll destroy the engine. I must say that I do prefer diesel - just because the engines are built better and will last longer than most any gas engine - and I do prefer the safety of the fuel - what I don't like about diesels is they are expensive on the initial buy, repair is expensive and requires special tools and most marinas in my area (Tenn.) don't carry fuel. In the rental business my focus was ease of service after a bonehead renter tore something up - thus we called outboards "clip on's" I could have a messed up lower unit swapped with a fresh engine in an hour - not so with the I/O. I sense most of the negative reaction with this concept is the appearance of the boat.

CapNjeff

Suggest you list your diesels in the classified section. BTW how many hours, RWC or FWC, have they been in salt, etc.

Houseboats weighing over 12,000 lbs will not handle properly with outboards, aluminum is much lighter. I realize many change just to do so. Many a houseboat had outboards but they were not planing hull houseboats. In this area it would ruin the resale, I for one would not want it on a Holiday but that is just my opinion. We tried it on a 36 Gibson once and you had to herd the boat. You cannot put the proper prop per weight ratio on and the Holiday was not designed for such. Seems like a lot of money to spend on an application to devalue the boat with the performance and handling characteristics impaired. Old Houseboater and I have discussed this many a time and we both agree that outboards are better left to non-planing hull houseboats. I have never heard of a twin V-drive being converted, I guess the Capt has one of the few if not the only one. I can see in a way a person with a toasted IO going for the dual engine setup if they just love the boat and have no desire for change. I for one like the V-Drive setup 10 to one over the outdrives and especially the outboards. I guess I am from the old school, as the handling of V's far exceeds the others on 98% of all applications. I even had a Gibson built when I was a dealer with a single V. It was the fastest boat single engine boat on the Lake but some could not put it back in the slip because they just could not get the fact that in reverse the stern went port. These are not meant for everybody. It is interesting about the Marinette being converted as they were famous for handling and the nice lines they had, very good boat. I have calls for diesel houseboats all the time but there are just not many around. They bring a premium price with Vs are not subject to the things you get in salt on outdrives.
pirate38158.2586111111

I would like to get a price on the units you have for sale as many people inquire about those type setups. 

Maybe I should clairify why we are thinking of twin 4 stroke outboards.A single screw is very hard to manuver in tight quarters and a Holiday Mansion has alot of windage.We navigate in alot of shallow water.The growth on outdrives is very bad in our area.Vapors,noise.Mantinence,and speed is not a factor because we cruise at about 10 mph.A bolt-on powder coated aluminum swim platform can be had for around $2,000 and I already own 1 Susuki 4-stroke that runs great.

So.. Your HM has a single I/O unit in it? Twin 4 stroke Outboards maybe OK compared to a single I/O. If maneuvering is the only reason have you considered a stern or bow thruster. That would not have the effect of lowering the value while providing maneuvering ability. Also they make very good paint for the drive. I use interlux BioLux.

Mounting outboards on the swim platform is probably not an option. You have to construct or obtain 2 standoff brackets for the outboards.  The swim platform goes away. You can have a ladder between the outboards.

By a swim platform poorbuthappy is referring one of these.

You could also get two single engine brackets and set them are far apart as possible. Poorbuthappy, if you are near the Ft Lauderdale area there is a 36'HM at Dusky Marine Center that is set up with two barckets. If I get by there in the near future I will snap a picture.