V-drive Versus Stern Drive

[Cadence]

Originally Posted by Cheechako

An inboard shaft drive is far better than a stern drive/ less maintenance in salt water. It doesn't matter if its a V drive or conventional.

The V-drive was probably only a comparison for having the engine weight aft. I think my son has my OMC Cobra someplace. A good unit for a trailed boat. For a boat kept in the water, I would not have one. Someone mentioned big OBs, look at the prices they command. Probably great units but $$$.

[skipmac]

Lots of very good and relevant points. There is no doubt in my mind that

Straight shafts are the simplest, most reliable option.

V-drives come in a close second for simple and reliable with a little additional cost. complexity and reduced access. The advantage for those trade-offs is pacing the engine further aft for better weight distribution and additional interior space for small to medium boats.

Outboards have excellent power to weight ratio, take up no interior space, very maneuverable but are expensive.

Sterndrives. Similar advantages to a v-drive but with the added complexity of the outdrive.

I've owned boats with all the above drives and except for outboards, have time cruising with them. Hands down my preference is an inboard diesel with a straight shaft for all the reasons that have been mentioned. However my experience and what I have seen and heard over the years a sterndrive boat can be a reasonable option, even one left in the water continuously.

If anyone has any data or statistics that show sterndrives have an unacceptably high failure rate I would be interested in seeing the information.

[Wolfgang6]

Originally Posted by valhalla360

........

Maneuverability: On a single engine boat, the stern drive will be better. On a twin engine boat I would give the edge to he inboard though not by a large margin.

The boat I am looking at is a Sea Ray 310 /320. I am told that for maneuverability in tight areas like a marina, the V drive is much better than a stern drive, making it more suitable for beginners like myself.

[skipmac]

Originally Posted by Wolfgang6

The boat I am looking at is a Sea Ray 310 /320. I am told that for maneuverability in tight areas like a marina, the V drive is much better than a stern drive, making it more suitable for beginners like myself.

Not necessarily. The stern drive moves with the steering wheel so you can direct the thrust left or right. This will allow you to make a very tight turn going forward, much tighter turn than you could make with a v-drive.

However with the propeller behind the boat on a stern drive the prop walk can be pronounced in reverse so you will back much better in one direction than the other. Depending on the boat, prop location and shaft angle you could see the same with a v-drive.

Just remember a v-drive or straight shaft boat doesn't change direction until the boat is moving (forward or reverse) and the water hits the rudder.

[Wolfgang6]

Originally Posted by valhalla360

......

Maneuverability: On a single engine boat, the stern drive will be better. On a twin engine boat I would give the edge to he inboard though not by a large margin.

I am looking at 30' + cruisers. Since I've not owned a boat in over 20 years so I am essentially a beginner. Maneuverability in tight areas such as a marina is why I am leaning towards a V-drive. Also, I expect to be doing the maneuvering all by my self, don't expect much, if any, help from wife and daughter. Should I also be insisting on a bow thruster ?

How many think I am over my head to get back into boating with such a big boat ... . I am though it is better to get what I want to keep long term than to have to change again in a year or two.

[ranger58sb]

Originally Posted by skipmac

The v-drive access is a huge pain and tightening the packing glands a real exercise in stretching and bending at odd angles while applying a heavy force. Otherwise it's a fairly simple, reliable system, comparable to a straight shaft.

That can be partially mitigated by dripless shaft seals.

Originally Posted by Wolfgang6

The boat I am looking at is a Sea Ray 310 /320. I am told that for maneuverability in tight areas like a marina, the V drive is much better than a stern drive, making it more suitable for beginners like myself.

Originally Posted by Wolfgang6

I am looking at 30' + cruisers. Since I've not owned a boat in over 20 years so I am essentially a beginner. Maneuverability in tight areas such as a marina is why I am leaning towards a V-drive. Also, I expect to be doing the maneuvering all by my self, don't expect much, if any, help from wife and daughter. Should I also be insisting on a bow thruster ?

How many think I am over my head to get back into boating with such a big boat ... . I am though it is better to get what I want to keep long term than to have to change again in a year or two.

You gotta start somewhere.

I don't know that I'd say maneuverability with a single V-drive is easier than with a single stern-drive. Different, but wouldn't say either is "better."

Maybe different with twins, but then would begin to depend on how separated the two props are. Close together doesn't give you as much "twisting" power. And usually twin stern drives are locked together, so you don't gain as much from their steerability as you do from being able to operate each prop in opposite directions. (There are some very new boats with separated stern drives, so each can function more independently; if your budget runs to newish boats, you might want to examine that option. Mercruiser syste, I think...)

Even if you mean to leave the boat "in the water" you could maybe add a lift system to your slip. Technically, that's easy, just $$$; depends more on your marina owner... but it's quite common, and speaks to issues with stern drives in salt water areas.

Twin inboards with straight shafts in a 34'+ boat start getting more easily maneuverable...

Twin inboard with pod drives (Volvo's IPS or Cummins' Zeus) are even more maneuverable.

And if you're young enough to know how to work a joystick and have one of those systems onboard (either pods, or more conventional with a thruster), you can learn to dock anything in about 20 minutes.

Bow thrusters are probably nice, but it's also prudent to know how to park the boat without a bow thruster. Starting out with one often leads folks to rely on it -- which is not bad of itself -- but then the operator often hasn't a clue how to dock if the thruster goes south.

And they can add expense. Usually a bow thruster can be retro-fitted. One approach would be do find your boat, learn how to work it, add a thruster later if you decide it's worth it.

-Chris

[valhalla360]

Originally Posted by Wolfgang6

The boat I am looking at is a Sea Ray 310 /320. I am told that for maneuverability in tight areas like a marina, the V drive is much better than a stern drive, making it more suitable for beginners like myself.

At that size, you are looking at twin engines. The only real trick to remember with stern drives is to keep the wheel pointed straight ahead and then they will work pretty much the same as inboards.
- If you crank the wheel hard over, you will get very little of the twisting motion from putting one in forward and one in reverse. This has to do with the geometry when turned hard over. The line of thrust gets closer together the sharper the turn.
- There will be a slight change with the props being further back but unless you switch back and forth from inboard to sterndrive, you won't know the difference.
- For the same model, the engine spacing will be the same distance apart, so that won't have an impact.

Maneuverability, isn't really a consideration when choosing:
- If you beach the boat, I would lean toward stern drives.
- If you want minimal maintenance, I would go inboard.
- If top end speed is important, stern drive
- Rack storage, I would go stern drive.

There are probably, other considerations but no right or wrong answer.

[darylat8750]

In that size boat I would like to have diesels. With straight shafts or v drive. I would only buy a v drive boat that had the v gear boxes mounted far enough forward of the engines that the stuffing box is not buried under the engine. I have a friend who twice had a "drip less" seal fail and it was good that access was easy. Maintaining a traditional stuffing box is no big deal if you can get at it conveniently. Reaching under a hot engine and adjusting by "brail" is not my idea of convenient.

If buying gas powered I would be strongly inclined towards outboards.

[Cheechako]

Originally Posted by Wolfgang6

I am looking at 30' + cruisers. Since I've not owned a boat in over 20 years so I am essentially a beginner. Maneuverability in tight areas such as a marina is why I am leaning towards a V-drive. Also, I expect to be doing the maneuvering all by my self, don't expect much, if any, help from wife and daughter. Should I also be insisting on a bow thruster ?

How many think I am over my head to get back into boating with such a big boat ... . I am though it is better to get what I want to keep long term than to have to change again in a year or two.

The outdrives will give you better manueverability in a close quarters. BTW, with that size cruiser and gas engines you could be talking maybe $100 an hour fuel cost. If you need to get there fast that's the price you pay. If you got a 32 ft trawler you would pay maybe $5 an hour in diesel, but only go 8 knots or so.

[tuffr2]

Interesting discussion. I wonder if the OP should also consider outboard motors as that is 90% of what I see in the Crystal/Homosassa River Area of Florida.



Sent from my SM-G360V using Cruisers Sailing Forum mobile app

[Cheechako]

Once you get up to 30 ft like he's talking.... OB's are about near their limit in avail hp... and are likely $20,000 each or more.

[tomrealest]

One issue with V drives is what brand boat they are in. In the late 80's Wellcraft made a 34 foot express, I think it was called a Gran Sport. The bottoms would flex and the V drives would blow out. I would check with one of the LARGE Marine transmission shops that the marina's send their transmissions out to be rebuilt to see what they would recommend NOT buying. I know their is one in Maryland not to far from Annapolis (maybe Edgewater? ) and there is probably one in Florida.

I would definitely get a V drive after I did my due diligence.

[Wolfgang6]

The sea ray 310 I am eyeing comes in V drive or Stern drive. Considering that I am leaving the boat in the water, looks like I'll get the V drive. My marina does not allow lifts and while the Chesapeake Bay I am at is mostly fresh water, I do plan to go to the southern part of it which is salt. Also plan to take it out of the bay to the ocean.

Sent from my SM-N920T using Cruisers Sailing Forum mobile app

[valhalla360]

Originally Posted by Cheechako

The outdrives will give you better manueverability in a close quarters. BTW, with that size cruiser and gas engines you could be talking maybe $100 an hour fuel cost. If you need to get there fast that's the price you pay. If you got a 32 ft trawler you would pay maybe $5 an hour in diesel, but only go 8 knots or so.

I think you are overstating the difference: We had a similar size boat to what the OP is asking about with V-drives. Assuming $3gal:
- We got about 1.5mpg at 20mph. That translates to about $40/hr with 20 miles covered in that hour. If we slowed down to 8kts, we could get significantly better.
- Most people we know with trawlers claim about 2-3mpg, so to cover the same 20miles, is going to cost $20-30 and take 2.5 times as long.

[Cheechako]

Originally Posted by valhalla360

I think you are overstating the difference: We had a similar size boat to what the OP is asking about with V-drives. Assuming $3gal:
- We got about 1.5mpg at 20mph. That translates to about $40/hr with 20 miles covered in that hour. If we slowed down to 8kts, we could get significantly better.
- Most people we know with trawlers claim about 2-3mpg, so to cover the same 20miles, is going to cost $20-30 and take 2.5 times as long.

a) the boat the OP is looking at has twin engines. At 30 ft they could even be twin 454's.
b) Hi stated size range is 30 ft. My 32 ft trawler burned 1.25-1.5 gal per hour.
c) Gas wont be cheap for too much longer.
d) That's all I know!