Sterndrive installation

Hi out there,

I hope I finaly found the propulsion method I want. As I am designing my boat, I went thru all sorts of propulsion I think the best way to get to move my boat will be using a sterndrive?

What do one have to consider if he would like to install such a system?

mounting height, is it depending upon engine, draft, what are the things to consider?

I was thinking about BRAVO one or Three together with a diesel marine engine +250HP.

Someone knows where to find some kind of template for cut-out(s)
Someone knows a good source for this material, if possible in Europe, the US will do also, but I dont know how this can be arranged with customs and transport, prices are very different in the US(better).

If anyone has any clue, allways welcome,

greetz,

 

The template comes with the drive alot of the time.I am not a Big fan of out drives.They are high maintenace pieces of aluminum crap with wimpy little shifter parts inside and it sits in salt water.The work of the devil.They should be outlawed.All the diesel out drive boats I see seem to have hatch problems they are allways wet with salt.they want you to change the oil and presure check them every 100 hours you need to get the boat out of the water to do it what a pian in the arse.stupid allways broken trim indacators,frozen and coroded in pins and hellmut.leaking and coroded stuck and siezed in trim cylinders.pain in the butt shaft and exhaust boots.It is a highly consintrated area of BS.High cost to them drives cost money you could get a Twin Disk trany for the price of those things ,that would last 20 years with hardly no maintenence.Yanmar has high performance diesels up to 315 HP with brovos on the back of them.If you get a yanmar you better keep the engine bone dry or it will not live.It is a good motor but It needs to be dryer than any of them.I hate to say this word but a V drive is better than a out drive and that ain't saying mutch.V drives are not unreliable, they just are in the tightest,mean and nasty mechanic hating engine rooms of all.good luck.And way to go for choosing diesel

 

Go to a jet drive and make everyone happy.

 

Now you guys are making me a bit nuts (kidding!) I went thru all this kinds of propulsion and I must say I did want to put in a jet unit, but there was the fact that there is not much to find in 2nd hand market in Europe. As this is a first tryout I can't permit to put in the new more expensive stuff.

The cheapest would be straight shaft, but this means more lost space (or not?) in the boat and has a bit a of manouverability problem.

Surface drive is more expensive than the rest? and is not for my speed specs. max 30-35kn.

so what options do I have?

 

Volvo Penta has a few very nice saltwater diesel outdrives that you might want to look at. If you're concerned about corrosion they've been experimenting with a composite-case drive that's kind of nifty.
Yes, PowerTech, sterndrives tend to require a lot of maintenance. They're designed that way to ensure profits for dealership service departments. That said, one of the boats I use often has been running the same OMC Cobra drive since 1987 with no major repairs that I'm aware of. Take care of the drive- change its oil, etc. and it will take care of you. (Also, if you're running a Merc it's often a good idea to add an aftermarket drive shower as they can run rather hot on the upper unit.)
Your main sterndrive options are the Merc B1/B3 and Volvo's Diesel DuoProp line. The B1 is a performance drive; it's intended for boats that run 50+ all day. Find a good dealer; they'll be glad to help you optimize your setup....
Straightshaft/V are more manoeuverable than you might expect if set up properly. I think there's a fair amount of good V-drive gear out there; they last forever.

 

the installation manual for 262 magnum efi gen + bravo three goes simplified on a single setup as follows:
transom should be 51 to 57 mm thick. locate and mark vertical centerline. find the X dimension on crankshaft centerline and determine X dimension on transom using a 90degree tool placed along bottomline. there is also the tape measuring method where the transom angle (between 10/13 to 16degree) must be known. you can use a template for cutting (shipped with assambly) or buy a separate transom drilling fixture kit. a keel if equipped should be removed 1.20 m forward from transom. and there is much more. try to get the installation manual and/or service manuals, its all in there. better have that done by a pro

 

All cut out drawings are graciously supplied by merc marine in either paper or electronic form upon request.Yeaaa!!!

 

Just so everybody understands what boats draw the most attention at a regatta of mixed sizes and types. Woodies with the engine in the center of the boat with a cockpit in front and behind plus a real +8' foward deck and the engine hatches open has NEVER failed to win the Spectators Choice Award by secret ballot or a show of hands. Yea, it is a Geezer boat. But it has workmanship, color and class. 1 subdued blue engine and transmission somehow reaches the classy desires of almost anybody who never owned a boat. I have never got a straight simple answer from most people. The drives are brutally simple to get any prop needed to get the maximum speed or people carrying capacity. You can shear off 6 shaft drives, throw a New Years party for 100 of your friends and still have $500 left over. Troubles ARE found by a child and repaired on a morning by his father. If you want to keep the marine economy rolling, go sterndrive

 

so if I understand you right, I should go V- drive, straight or jet? has anyone ever heard of a duoprop for V-drive or straight shaft?

greetz,

 

Marshmat. My 2002 250 hp Alpha 1 setup after draining the 38 gallon tank in 3 hours, has never heated enough to discolor the algae on top or given off water vapor. What kind of load is needed to overheat it? I think --I know I have a lead foot.

 

I'd have to agree with Cyclops that if you want cheap and reliable, go shaft- and if you want attention, mid-engine is sure to get it.
About the sterndrive temperature problems- Overheating's a lot more common on Bravos and other high-speed drives; smaller drives tend to push slower boats and so more of the drive is in the water. If you're running fairly light and fast, with a lot of bottom out of the water, that's when you'll get overheating. Also with big high-torque engines like a 7.1 or bigger.
Danielsan- I've never actually seen coaxial counter-rotating props on anything other than a sterndrive. The main advantage of the duoprop thing is that it eliminates torque steer at most speeds. It depends on the boat what is most efficient; generally though, a straight shaft wastes less power than a V-drive, which is itself better than a sterndrive. I'd suggest you decide first whether you want the engine in the middle or not. If so, go shaft; if not, it's down to V or sterndrive. (Sterndrives tend to trailer better, although V's are often more efficient and are certainly better for skiing/towing).

 

Marshmat. It is a 18.5' Chap and runs completly on it's pad @ 52 mph, to the point of being trimmed out so it does the " Cobra Dance" very slowly. Any more trim out is a loss of speed. True, I only hold it at that speed for 1 or 2 miles. Is the short ? time the safety valve? Thanks.

 

Sounds like you've got a pretty sweet rig there, Cyclops.... 52+ on a 250hp alpha, that is really nice....
From what you describe it sounds like your rig's running plenty cool. The Alpha has a reputation as being a solid little drive, and 200-250hp is right in its sweet spot. I think the drive temperature problems are more on the bigger drives, when you run 50+ for long trips, or when you're pushing a really heavy boat- neither of which seems to describe your zippy little rig.

 

A word to all us boat experts. I let my wife pick this boat at a large boat show. She grudgingly let me pick the engine. It spends most of it's time anchored 300 to 1/4 mile from it's dock as she reads a book in the bowseat and I stretch out completly on the stern sun pad and cat nap. Team work. I live in the other boat with old guys fishing.

 

Diesel with bravo 3. If outdrives are evil why are 90% of boats over 20 ft using them. I have had only one failure in my lifetime of boating and it was due to my stuppidity.