|Topic Review (Newest First)|
|11-10-2006 10:09 AM|
In addition to the excellent advice above, keep in mind (aside from the aesthetics of the outboard hanging off the back) that you need to consider reinforcing the transom area for the new bracket - if the boat was designed for an inboard the transom is likely not meant to take the stresses and loads as is.
Unless we're talking about a 25-27 foot boat, I'd stick with an inboard for a host of reasons.
|11-10-2006 09:56 AM|
The other problem with having an inboard that is non-functional is the additional weight it adds to the boat. Same with having an outboard attached to a boat with an inboard. A good four-stroke outboard is several thousand dollars, and that may go a long way to fixing the inboard engine.
My boat was designed to use an outboard, and as such, allows the engine to sit low enough that the prop coming out of the water is almost non-existent as a problem.
The other problem with an outboard on a sailboat is how to control the throttle and steering on the outboard. That can be a huge problem if the outboard is mounted low enough to keep the prop in the water...
|11-10-2006 09:50 AM|
Regardless of the size of your boat, I think you'd be much better off keeping an existing inboard in place. If the engine needs work, repair it, if its toast, have it rebuilt, you'll get most of any cost back when you sell the boat. An inboard is a much more servicable auxhilary than an outboard, which is the reason that buyers pay a premium for such. Trying to power into rough weather with an inboard can be difficult, in the same weather an outboard could be useless, even with the mandatory long shaft, the prop is out of the water half the time...
27' seems to be the length where builders begin switching to inboards...
|11-10-2006 03:54 AM|
|sailingdog||While the electrics can be a problem, especially if you previously had a high-output alternator attached to the previous engine...I don't think that is the case here. Some of the four-stroke motors have a decent alternator on them. The Honda 20HP I use has a 15 amp alternator, and that's generally all I need, since most of my power is suppied via two solar panels.|
|11-09-2006 10:14 PM|
|Goodnewsboy||I'd think a while about replacing an inboard with an outboard. Esp. about fuel supply and electrics.|
|11-09-2006 09:47 PM|
outboard longshaft question
I recently bought a 27 lancer with a 9.9 merc long shaft. I am transfering engine to 14 foot aluminum for temp dinghy. Must motor be mounted at transom height or raised on transom to certain heigt for running?
|04-22-2006 01:26 PM|
A couple of problems you may run into with using an outboard, even a long-shaft version on an outboard bracket, is that most boats will have a problem with keeping the prop of an outboard, mounted at the stern in the water. You might be better off using an outboard well, a bit further forward. Not only would this prevent having the 100 lbs of outboard hanging off the very stern of the boat, but it would probably allow it to grip the water much more efficiently. A marine surveyor or architect can give you a better idea of how well the boat would work with a stern-mounted outboard. The stern would probably also need some structural reinforcement to handle the weight and power of the outboard.
I would strongly recommend that you go for a four-stroke design, as they are quieter, cleaner, and more fuel-efficient than the two-stroker varieties.
You don't mention the length, displacement or size of the vessel in question, or how large the Yanmar diesel that you are looking to replace was. The horsepower to boat size ratio of diesel engines to gasoline engines isn't quite a linear one, as the diesel engines generally have a lower rpm and higher torque curve than the gasoline engines.
Most outboards have a very limited selection of props they can be used with, and finding one that has the appropriate pitch and power rating for your boat may be an issue.
|04-21-2006 05:16 PM|
|hamiam||A couple of thoughts. My guess is that going from an inboard to an outboard is actually quite a project. I take it you intend to remove the old engine and tank? This will, of course, effect the weight of the boat and also its balance as, im guessing, it was designed with the assumption that it would carry an inboard. Also, I dont believe you can just slap on outboard mount on the transom and mount an outboard to it; I would imagine that the hull needs to be reinforced in that area both due to the weight of the engine and the force it will exert on the hull. I agree with the posts above regarding a long shaft; typically you want that prop as low in the water as possible so it is driving as often as possible. You have two basic choices in outboard: 2 cycles and 4 cycles. Each has its own advantages and disadvantages. 2 cycles require a gas/oil mix and 4 cycles drink pure has. Typically 2 cycle engines are cheaper in initial cost, less efficient than 4 cycles, more polluting than 4 cycles and lighter than 4 cycles which can be a big advantage on, say, a dingy engine. 4 cycles typically are more costly, less polluting, more efficient, and have better life. Ive had many of the engines you listed above. My favorite was the Honda engines that I have owned; they are expensive but worth it in my opinion as they offer a long life and are relatively easy to maintain. I currently have a Nissan 9.8 which is the lightest engine I cud find in its power range as I need to take it on and off my dingy with some regularity. I would suggest talking to a marine engineer or surveyor before walking down this path. Good Luck.|
|04-21-2006 03:31 PM|
Just replaced my old '76 Johnson long shaft outboard with a new Mercury longshaft 6 hp. four stroke for my Georgian 23. With the trade in it came to $1500.00 canadian. I found it difficult to find a half decent motor at a reasonable price in the used market, and I didn't want to take a chance with someone elses problem in the middle of the lake. So for me in the end it was better to buy new and get the three year warrenty and peace of mind for a few extra bucks. s.v. Arvore Blues
|04-21-2006 01:21 PM|
As a point of reference, I have sailed 26' water ballasted Macgregor for 15 years. Ballasted and provisioned, it displaced about 4000 lbs. I drive it with a 9.9 hp Johnson which seems to be plenty. At full throttle, the boat wobbles off course and is impossible to steer.
I've crossed all the Great lakes in it, sometimes under motor. Never a problem. Also, I have motored (or at least tried) into 6' seas. As the boat pitches over the waves, the prop leaves the water and I lose drive. I don't think there is any way to avoid this. You can't get the engine low enough to keep the prop in the water on a crest and keep the engine from being drowned in the trough. It's a rare occurence though. The only times I have experienced this is when attempting to motor into a river with wind opposing water flow. In open water with high seas, I'm under sail.
I don't know which engine is best but be sure parts are availble for whatever you buy. I have an '80s vintage dinghy motor that I can't repair for that reason.
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