The Great Debate

I'll agree with that note that most of the engine shutdowns I've experienced in my life on a twin haven't been the fault of the engine so much as an ancillary component attached to it or a driveline issue that caused loss of use of that engine.

Causes of engine shutdowns I've experienced that I can remember:

• Sucked debris onto water intake causing loss of water flow and engine shutdown (on the way back into the dock anyway, so it was resolved after returning to the dock on one)
• Failed fuel pump causing an engine to stop running
• Stuck closed thermostat causing a quick rise in temp and an engine shutdown
• Most recent one was a transmission failure. Stripped teeth on the stationary plate in the reduction planetary. No prior symptoms, the trans went from working fine with no noises, etc. to producing no drive instantly. Engine on that side was running perfectly fine, it just couldn't do anything useful.

No question "stuff happens" ,

Internal shaft bearings are made in a split style that can be totally renewed with just a set of box wrenches , no hauling required. Not cheap , but good insurance.

It is my belief that overbuilding is always worth the effort. LUCY our 50ft US Navy Utility was built to military standards.There is a difference between repairs, PM and owner desired changes.

A hyd capstan, an autopilot and a 135A truck alt. were some of my changes.

Dry stack and keel cooling were already aboard.

We ran both loops, the Right using Lake Champlain and the Left down the Miss with only PM oil changes.

Over 1,500 hours enjoying the USA waters instead of repairing "stuff".

The tandem engine single shaft is not un-stopable , but should help.

If folks would like to participate in a less work , more reliability concept cruiser discussion, who will begin?

FF said:

No question "stuff happens" ,

Internal shaft bearings are made in a split style that can be totally renewed with just a set of box wrenches , no hauling required. Not cheap , but good insurance.

It is my belief that overbuilding is always worth the effort. LUCY our 50ft US Navy Utility was built to military standards.There is a difference between repairs, PM and owner desired changes.

A hyd capstan, an autopilot and a 135A truck alt. were some of my changes.


Dry stack and keel cooling were already aboard.


We ran both loops, the Right using Lake Champlain and the Left down the Miss with only PM oil changes.


Over 1,500 hours enjoying the USA waters instead of repairing "stuff".

The tandem engine single shaft is not un-stopable , but should help.


If folks would like to participate in a less work , more reliability concept cruiser discussion, who will begin?

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The shaft in question carried 60,000 shaft hp at full power.

Single engine guys are more comfortable in the engine room lol. I hate going down lol. That’s me! I pay for preventive maintenance because I’m a big guy.

I was happy that Sunday afternoon when going north up the St John past Bryant on Fleming Island that I had twins in my 36 GB when one started seriously vibrating. Took it to idle and went home. I really didn’t want to go in the river and see if I got a dinged prop or a crab pot or something else.

As many members have said it’s what you plan to do with the boat. In this boat I want to go up the east coast and down to the Bahamas and maybe fort Jefferson. Not going to Hawaii or across the pond. Done that in large Grey vessels and not what I plan for this one.

Twins are nice for maneuvering without the expense and complexity of thrusters. And I got my first ‘mostly‘ docking with one engine with this boat on Sunday. Glad the wind was calm.

That said for people who are reading this who do not yet have a boat. I Have two comments. Unless money is really no object. 1 Do a budget. Incremental cost on a twin is there and the less you do yourself the bigger it is. On an older used boat figure some rediculous percentage of the cost every year. 20%. 30%? Yeah really

Twin or single spend some quality time in the engine room. Even if you are not going to be changing pistons in a seaway, you MUST check oil and fuel filters every day you get underway. I lust after an engine room with better head room and outboard access every time I go there. If you really can’t fit or don’t want to go there rethink the entire trawler thing. Unless it really is going to be a boatominium and The Who cares about that stuff down there.

Oh another non engine engine failure, the admiral pulls you from the basement after you opened the top of the rancor and before you tightened it back down. And you have a senior moment and get underway.

dhrowe said:

Twins are nice for maneuvering without the expense and complexity of thrusters.

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I would have to say that another engine is significantly more expensive and complex than thrusters......as you were!!!

JVCalifornian said:

Single engine guys are more comfortable in the engine room lol. I hate going down lol. That’s me! I pay for preventive maintenance because I’m a big guy.

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We have twins, and it would be so much nicer to have just one engine in the middle for access. It's nothing to do maintenance on the inboard sides of our engines (zinc's etc.), but I curse like a sailor every time I have to wiggle to the outboard sides to do stuff.

Group9 said:

We have twins, and it would be so much nicer to have just one engine in the middle for access. It's nothing to do maintenance on the inboard sides of our engines (zinc's etc.), but I curse like a sailor every time I have to wiggle to the outboard sides to do stuff.

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My next move up will be to the low to mid 40 foot coastal yacht.
My general thought would be traveling at less than 10 kn nearly all of the time.
I would like a single and the market is stuffed with twins.
Maintenance would be the largest concern with twins as I can control the speed and fuel burn rate.

Baker said:

I would have to say that another engine is significantly more expensive and complex than thrusters......as you were!!!

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I completely agree a lot more expensive, except I don't know about getting home on thrusters!

If you have twins in a 40 ish boat, you can maneuver pretty well without thrusters. Or you can be an old salt and spend LOTs of practice and just go with a single engine an no thrusters. ( I am not saying anything derogatory about people who have years more helm experience than I do. Just jealous) Especially when I have some wind or tide I am happy with twins. - cause I have them. I stepped up from a 28 foot sailboat to the GB 36 and twin screw docking is almost always a quiet relaxed event.

I can normally dock with my mantra that nobody ever got hurt from going too slow. Or aborting and going around again!

BUT I think I will do some more single engine docking practice the next time we go a voyaging.

dhrowe said:

If you have twins in a 40 ish boat, you can maneuver pretty well without thrusters.

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THe funny thing is I just went from a twin and no thrusters to a bigger one with BOTH bow and stern thrusters. The thrusters to me are just a convenience...basically when I decide to get lazy. They never factor in to my docking plan. I have one friend who gets a little irritated with me when he is on my boat because I don't use them. He might even be handling the lines and I can hear him yelling..."Use your thrusters dumbass"...hahaha.

I still don't quite understand stern thrusters on twins. I can't think of a situation where I've ever thought it might be useful. I have had the "a bow thruster might be handy right now" thought a couple of times while backing into a tight slip with a strong crosswind though.

rslifkin said:

I still don't quite understand stern thrusters on twins. I can't think of a situation where I've ever thought it might be useful. I have had the "a bow thruster might be handy right now" thought a couple of times while backing into a tight slip with a strong crosswind though.

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Did you follow that recent stern thruster thread?? Stern thrusters are about half as expensive to install than bow thrusters. THe poster's question was if the extra money involved was worth the "value" of having a bow thruster.

With that said and to answer your question, you have to approach the situation differently and the stern thruster becomes quite useable. Since I have both, I now understand the value of a stern thruster. Probably the biggest thing is the stern is significantly less affected by the wind so thrusting up into the wind is easier with the stern. But the real answer is how you approach the situation. Everyone on that thread that had stern thrusters said they were quite valueable. The only dissenters on that thread were people that didn't have them...with the same sentiment as you. Bottom line...if you don't have a stern thruster, you just don't understand.

I haven't seen that thread. With a single, I can definitely see the stern thruster being useful. But with twins, I've never felt like I'm in a situation where I don't have enough ability to move the stern sideways with the engines (and rudders if needed). There's definitely less ability to move the bow around though, at least without moving the whole boat in the process.

rslifkin said:

I haven't seen that thread. With a single, I can definitely see the stern thruster being useful. But with twins, I've never felt like I'm in a situation where I don't have enough ability to move the stern sideways with the engines (and rudders if needed). There's definitely less ability to move the bow around though, at least without moving the whole boat in the process.

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Give that thread a read. It's a long one though...

Many boats I have handled with tunnels and large keels don't walk sideways well to begin with and maybe not at all in some conditions.


A thruser (stern or bow) in an engine out situation can be a winner too.

rslifkin said:

I haven't seen that thread. With a single, I can definitely see the stern thruster being useful. But with twins, I've never felt like I'm in a situation where I don't have enough ability to move the stern sideways with the engines (and rudders if needed). There's definitely less ability to move the bow around though, at least without moving the whole boat in the process.

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Well, you might think differently if required to put a 45' yacht into 50' of side tie dock space. Or, in easing away from the wall inside the lock when the wind is blowing toward it.

Stern thrusters aren't a necessity but they can be very helpful.

BandB said:

Well, you might think differently if required to put a 45' yacht into 50' of side tie dock space. Or, in easing away from the wall inside the lock when the wind is blowing toward it.

Stern thrusters aren't a necessity but they can be very helpful.

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For that first one, my boat pivots fairly well around the bow with careful use of momentum, so normally I'll rotate the boat into place (pretty much stick the bow where I want it and rotate the stern into place, but with a bit of momentum carrying the boat sideways so it slides into place as I rotate). Basically instead of coming up and just sliding in, I'll come up and make a 180 into the spot if it's tight as I can carry more sideways momentum and need less length that way.

Personally, I wouldn't go for a space quite that tight unless in pretty calm conditions, but I've done spaces slightly bigger without issue.

Getting off a face dock or wall with the wind blowing me on is usually not much of an issue. If it were a tight spot, then I might be wishing for thrusters. But typically I'll just kick the stern out a bit and work my way off (diagonally backwards if needed). If the wind is so strong that a few good blasts of throttle and working quickly isn't enough to do the trick, I'd generally be docked or anchored and waiting for better conditions anyway.

In any of those situations, I think I'd get more use out of a bow thruster than a stern thruster. Having a bow thruster would let me walk the stern over with the engines while using the thruster to keep the boat from pivoting by moving the bow over along with the stern.

BandB said:

Well, you might think differently if required to put a 45' yacht into 50' of side tie dock space. Or, in easing away from the wall inside the lock when the wind is blowing toward it.

Stern thrusters aren't a necessity but they can be very helpful.

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Under certain conditions I agree, but not all the time.
Years ago I was asked to dock a 32 footer in a parallel spot with a boat and half width between parallel docked boats near the end of the alley. conditions were right to back in with twins, but who knew when time to leave and no room to do 180 to back out.
Then there was the time I docked a 30 foot sail boat under sail power parallel. So there are always circumstances that allow out of the norm.
Thrusters would be a welcome tool if made available for free as I have yet to say, gosh I wish I had thrusters. They are a convenience, another tool.

Amazing how many great boat handlers are on TF......yet the shows that go on at every marina......

psneeld said:

Amazing how many great boat handlers are on TF......yet the shows that go on at every marina......

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I'm sure we've all had a bad day and been the show at some point. I almost was when bringing the boat into the lift pit for haulout last fall. I must have just been having an off day, but it took a couple tries to get it lined up right to nose in.

But realistically, most of us on here probably use our boats far more than the 6 times per summer boaters that are likely responsible for most of the good shows. Many of them seem like they figured out how to sorta-kinda get the boat in the slip and then just never tried to improve beyond that. So compared to that, most on here likely have better skills simply due to more practice.

Not really true....many are regular boaters with better stories than actual performance....

psneeld said:

Many boats I have handled with tunnels and large keels don't walk sideways well to begin with and maybe not at all in some conditions.


A thruser (stern or bow) in an engine out situation can be a winner too.

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Kudos to a good post. On topic. Look forward to more useful posts.

Group9 said:

We have twins, and it would be so much nicer to have just one engine in the middle for access. It's nothing to do maintenance on the inboard sides of our engines (zinc's etc.), but I curse like a sailor every time I have to wiggle to the outboard sides to do stuff.

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For that very reason I generally won't do engine maintenance unless my wife or somebody else is with me -- because I might actually get stuck between the hull and the engine. I'm not huge, but I'm big enough that I have to tightly wedge myself against the hull like a bullet in a rifle barrel to access anything on the outboard sides and I'm not confident I'll always get myself out. I don't want to be tapping on the hull yelling for help, drinking bilge water to survive until somebody walks by. My 11 year old is about 80 lbs. and he already does a great job changing the port engine oil filter for me, outboard side. He comes in very handy and only charges me some Pokemon cards.

(I used to be a commercial diver in a previous life and we did interior pipeline inspections, so tight we just about had to grease our shoulders. The closest I ever came to drowning was the day I squeezed myself into a pipe wearing a Desco mask instead of a helmet because a helmet wouldn't fit into the pipe. About ten feet in my harness got caught on a pipe seam somewhere down around my lower back. I couldn't back out with the harness snagged on the seam, couldn't reach the harness because I couldn't move my arms back there, and then as I was trying to squirm my way free I forced the mask halfway off my face so the mask filled with water and bubbles, and I couldn't move my arms to reach my face to put it back. Only the grace of God got me out of there in time, back down the pipe and past the intake fins. I literally have no memory of how I got out of there, it's a complete blank. One second I was about to drown in that pipe and the next second I was coughing and sputtering at the surface. Alcoholics talk about blackouts, that escape is a blackout for me, like somebody simply deleted those few seconds of video from my life history. I'm not claustrophobic but I'll never forget that feeling and I don't like it. Okay, end of story, back to our regular programming.)

I’m the guy that started the thread about bow vs stern thrusters. Wrong title - I should have chosen a more neutral subject line. That being noted, having owned a 44 Tolly with both bow and stern thrusters, maneuvering our current Bayliner 4788 pilothouse with no thrusters, and playing with another 4788 using only the stern thruster (had both) I will venture the following:

1. There is no substitute for honing docking and undocking skills. Practice - including assessing wind and current, setting proper lines, and *managing fender placement - actively if necessary* (assumes at least one crew).

2. Any thruster is a great docking aid when conditions or crew or lack of crew make docking or undocking overly challenging.

3. For the 4788 wind profile, tiny/no keel, and soft bilges the stern thruster is, for practical purposes, as effective as a bow thruster - at least to the extent we tested the proposition.

There isn’t a point to defend and my question was one of simple economics. Would the cost premium of a bow thruster create value in proportion to the extra expense? Assuming a 50%+ premium and based on our admittedly simple empirical testing: No.

I don’t mean to derail this thread any further than it already has been and anyone can feel free to post on my original “vs” thread. Thanks for the references folks. Bye for now. G

rslifkin said:

For that first one, my boat pivots fairly well around the bow with careful use of momentum, so normally I'll rotate the boat into place (pretty much stick the bow where I want it and rotate the stern into place, but with a bit of momentum carrying the boat sideways so it slides into place as I rotate). Basically instead of coming up and just sliding in, I'll come up and make a 180 into the spot if it's tight as I can carry more sideways momentum and need less length that way.

Personally, I wouldn't go for a space quite that tight unless in pretty calm conditions, but I've done spaces slightly bigger without issue.

Getting off a face dock or wall with the wind blowing me on is usually not much of an issue. If it were a tight spot, then I might be wishing for thrusters. But typically I'll just kick the stern out a bit and work my way off (diagonally backwards if needed). If the wind is so strong that a few good blasts of throttle and working quickly isn't enough to do the trick, I'd generally be docked or anchored and waiting for better conditions anyway.

In any of those situations, I think I'd get more use out of a bow thruster than a stern thruster. Having a bow thruster would let me walk the stern over with the engines while using the thruster to keep the boat from pivoting by moving the bow over along with the stern.

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You can't pivot a 45' boat into a 50' spot. Sometimes that's the assigned space. I'd never choose it and without bow and stern thrusters, I'd never try it.

In the second scenario by kicking the stern out you're going to be pushing the bow in and may well end up with scraping. Inside a lock your options might be limited.

I've seen a lot of people really struggle and some damage in scenarios like those two.

BandB said:

You can't pivot a 45' boat into a 50' spot. Sometimes that's the assigned space. I'd never choose it and without bow and stern thrusters, I'd never try it.

In the second scenario by kicking the stern out you're going to be pushing the bow in and may well end up with scraping. Inside a lock your options might be limited.

I've seen a lot of people really struggle and some damage in scenarios like those two.

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We've gone into a 42 foot side tie reciprocal slip with our 40 foot single more than a few times.
Our anchor overhanging swim platform of boat in front and our swim platform under bow of boat behind.

You gotta' do what you gotta' to get into free reciprocal docks in the PNW.

When we leave a side tie, the wheel is turned all the way towards the dock and I put it into forward momentary to turn the bow towards the dock and the stern pushed out. Then floor it in reverse momentary and back to forward and back to reverse, forward repeatedly until angled from the dock enough to clear the boat behind.

The bow never touches the dock because of the tapered bow. If wind is pushing us onto the dock then a spring line is used and my wife uses a fender to keep us from hitting the dock and to create a pivot point.

In the locks, definitely several fenders on the bow.

syjos said:

We've gone into a 42 foot side tie reciprocal slip with our 40 foot single more than a few times.
Our anchor overhanging swim platform of boat in front and our swim platform under bow of boat behind.

You gotta' do what you gotta' to get into free reciprocal docks in the PNW.

When we leave a side tie, the wheel is turned all the way towards the dock and I put it into forward momentary to turn the bow towards the dock and the stern pushed out. Then floor it in reverse momentary and back to forward repeatedly until angled from the dock enough to clear the boat behind.

The bow never touches the dock because of the tapered bow. If wind is pushing us onto the dock then a spring line is used and my wife uses a fender to keep us from hitting the dock and to create a pivot point.

In the locks, definitely several fenders on the bow.

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The bow taper is exactly the key to pivoting the stern out.

The pivot point on most boats is 1/3 back from the bow.

On my single, the bow thruster is a God-send. Saves the transmission and helmsman.

psneeld said:

Amazing how many great boat handlers are on TF......yet the shows that go on at every marina......

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But, that's those other guys! Not any of us!