Engine Dilemma

[neilf39]

I currently have a Bukh DV20, which is 37 years old, in a Konsort. It has had two head re-skims/ring changes (1992 and 2013). Only problems I have had since I owned the boat from 2013 are, not starting (faulty connection to starter solenoid), leaking fine filter housing (replaced), and oil leak from front oil seal (seal replaced). It starts within 5 seconds of turning over and been across to Brittany several times running up to 17 hours at a time non-stop, so is a reliable old thing. It is a bit noisy and there are a couple of small rev ranges where there is a lot of vibration or a bit of a noise from the gearbox so I avoid those. I have had the engine aligned both in and out of the water, engine bearers are relatively new, and there is no play in the cutless bearing which was also new a couple of years ago, so not sure what causes this but it is annoying. Anyway, apart from this and being a bit noisy, the only thing I find is that punching into the usual Solent chop and headwinds (which I do a lot based in Chichester Harbour) is that I could do with a bit more power to make decent headway. I would guess my engine may have lost a few horses given its age.

I am thinking of putting in something with a bit more grunt. I was thinking of a new Beta 25 (maybe Yanmar), or, to save money and avoid having to change much, get a very low hours ex-lifeboat Bukh DV24 (from Marine Enterprises) and just drop it in. I think I would need a new prop at the very least with either, and for the Beta probably a new shaft and various other bits to convert over to it. So probably £9k plus for new and £3-4K plus for the Bukh.

So, given I have an engine that still seems reasonably fine is it really worth doing either of the above? Would 4-5HP make a noticeable difference? Is it worth considering the Bukh DV24, or, if I am going to do it go for a newer, lighter, quieter, engine? If I do upgrade I will definitely be keeping the boat long term.

As added info I currently get about 5.5kn through the water at 2500 revs in a flat sea with a clean hull/prop (prop is a fixed 14x13 2 blade).

I would be interested in your views.

 

[MoodySabre]

I'm of the if it ain't broke.....faction.

I would consider the cheaper engine but with a folding prop. Better motoring and better sailing. And more soundproofing.

 

[dave_gibsea]

Interesting question which I think we have all pondered over at one time or another. I too seem to spend a lot of time with headwinds, one thing I know is that I prefer to sail upwind than flog into a headwind and sea under engine. Sailing to windward comes with the territory if you week-end in the Solent. I guess the question is: will a bigger engine provide more enjoyment or peace of mind? It won't necessarily get you there any faster. If we were bothered by that we we would travel via a sailing boat. Maybe a better alternative is to look at the rig? are the sails getting a bit tired? Might a small "Solent" or Working jib help? I bought a working jib some years ago and it transformed the boats windward ability on those days when you need a lot of rolls in the Genoa.

As for the old engine, in my experience if you have a good reliable engine in your boat hang on to it, there are plenty of unreliable ones out there that cost lost to run and fix. Maybe its a case of "if it aint broke...."

 

[neilf39]

I do quite often sail as it is usually at least as quick to tack as it is to motor direct, and a bit more comfortable. However sometimes there is chop without wind, or the tides and wind conspire to make motoring a better option. She sails really well. I can get up to 7 knots sailing 40 degrees off true wind with the wind at 15+ knots.

 

[seumask]

For what its worth we have the Bukh DV24 in the slightly bigger brother, a Fulmar, that was a new engine in 98 ( Bukh 20 replacement). Its not as smooth or as quiet as a modern engine, but with the addition of a folding 2 blade prop we saw an appreciable increase in performance under sail and more speed under motor at lower revs as we pitched up the prop by 2"'s from the previous fixed 2 blade.
However on the acid test of punching to windward up the Solent under engine, (very rare as we usually only do this under sail) we only saw a small improvement and I think that largely related to the difficulty in pushing a heavy boat through steep seas and head wind, so I suspect only a combination of much bigger engine and more boat length will ever make much of a dent in that test!
IMHO that's a very big bill compared to the value of the boat or some better sails, and if your familiar with yours I suspect a bit of checking and fettling it over the winter will restore your confidence in it.

 

[lw395]

I think you would need to be very committed to your boat to spend £9k on fitting a better engine, when the current one still works.

If you want to make better headway, perhaps a bigger boat with a bigger engine?

Or, if the real issue is that you are eager to motor away from your mooring, consider re-locating the boat?

 

[BabaYaga]

I am thinking of putting in something with a bit more grunt. I was thinking of a new Beta 25

Would 4-5HP make a noticeable difference?

I have a 20 hp Beta 722 in a boat that I believe is similar to yours in LOA and displacement. And I consider my boat being, if anything, over–powered rather than the opposite.
So unless your Bukh has lost a large number of horses over the years, I think you would gain very little for that big outlay.
Perhaps spending some of that money on a three bladed feathering prop could be worth considering.

 

[vyv_cox]

I replaced a Bukh 20 with a Yanmar 3GM30F in around 2000. Very es2sy change, only needed to raise the beds by about 25 mm. For a few months I retained the original prop that worked fine. Exhaust hose changed but that's about all. Well worth doing, saved 100 kg and gave lots of space above the engine.

 

[Stemar]

You may not need to change the shaft. I went from a single cylinder MD1 to a 3 cylinder VP 2003 and was able to use the same shaft.

However, I'm also in the "If it ain't broke" camp. Are you getting full revs at sea? If so, your engine's still giving full power or, at least, isn't over propped for the power available. If not, does your prop match what a prop calculator (eg https://www.vicprop.com/displacement_size.php ) says you should have? A lot of the time it's advantageous to be a little over propped as it gives more relaxed cruising, but punched a sea where you're not making hull speed, you're better off being a bit under.

If you are down on what the book says, getting the injectors checked would be my first step. The pump's a more expensive thing to refurb, but doing both on my little boat when I first bought her doubled my cruising speed. The poor thing wasn't used to working so hard, so she complained by pumping all her oil out into the bilges, resulting in the engine change mentioned above, but that's another story...

If you don't need to change the engine, a new feathering prop may help and is a lot cheaper than a new donk. The Brunton is supposed to adjust itself to conditions, making the best use of the power available to it in any conditions, but the price is a bit eye-watering. A kiwi prop has a fixed, but easily adjustable pitch and is a good bit easier on the wallet

 

[oldharry]

There's two questions here: 1. Is your old engine reliable, and likely to remain so for the forseea le future? If so is there any reason to change it, other than it doesnt push the boat quite fast enough? If not check whether a change of prop might not give you the boost you seek. A more efficient prop can make a lot of difference.

2. How much power does your hull need to push it at waterline speed? What size engine do people put in Konsorts these days? If there is a big jump in the HP needed to acheive waterline speed with a comfortable margin for rough water, headwinds etc, then is the boat worth spending that much money on? You will lose a large part of it against the resa?e value. It can be a lot better investment to buy another boat with a more powerful engine already in it, then you do not lose the from new depreciation.

 

[neilf39]

Thanks to all for the comments so far. Food for thought. I have been overtaken by other Konsorts and even a Centaur when under motor so either they have bigger engines or my power is down or prop wrong. It is the prop that was fitted when new so presumed it was matched at the time

 

[Mister E]

You have given me an idea to try, as on the back of our boat there is an outboard bracket (drop down). This is for the motor used for the tender.
I may just try starting this up and seeing if that gives a bit of extra shove against the current, a bit of a Tesco thing (every little helps).
It may be like the real Tesco (very little help).

 

[Champagne Murphy]

You have given me an idea to try, as on the back of our boat there is an outboard bracket (drop down). This is for the motor used for the tender.
I may just try starting this up and seeing if that gives a bit of extra shove against the current, a bit of a Tesco thing (every little helps).
It may be like the real Tesco (very little help).

If its in the wash from the main prop wont it have interesting effects on flow and such like? More cavitation?

 

[Tranona]

If you want to check performance suggests you carry out some structured timed runs, logging speed through water at 200rpm intervals from 1800 to maximum of 3000 (or whatever maximum you can achieve) You should be able to get near hull speed (high 6's) at around 2800 rpm and cruising between 5 - 5.5 in the range 2000-2300 rpm.

 

[Tranona]

You have given me an idea to try, as on the back of our boat there is an outboard bracket (drop down). This is for the motor used for the tender.
I may just try starting this up and seeing if that gives a bit of extra shove against the current, a bit of a Tesco thing (every little helps).
It may be like the real Tesco (very little help).

Won't work as the boat will already be going faster than the outboard prop could push it so all you will be doing is stirring up some water.

 

[Dull Spark]

The engine vibration you mention could be exhaust valves that have blown. It's easier to take the cylinder head off and check/replace than to change the engine.
Even easier is to keep slime and crud off the propeller. By this time in the season, you may have more than you think growing on it. It doesn't take much to reduce propeller thrust. It may be worth checking that the propeller and engine are properly matched.
Good luck!
Remember that hull speed for a Konsort is only about 6.5knots. To go much faster, you will need ever increasing power for little return.

 

[Stemar]

Remember that hull speed for a Konsort is only about 6.5knots. To go much faster, you will need ever increasing power for little return.

Correct, but more power will be needed to maintain that speed, or close to it when punching a head sea. It's generally more comfortable to slow down, but if you're trying to get into a harbour against the ebb, that may not be desirable

 

[Rafiki]

I changed from a Bukh 20 to a 2nd hand Bukh24 from a company in Poole, possibly Marine Enterprises. A few points:
1) it was much smoother, quieter
2) nothing else was changed, I used the existing wiring loom, shaft, prop and feet ( the feet had just been changed by me)
3) the 24 started much better when cold
4) I removed most of the woodwork to assist in removal of the old engine, but the actual swap-over and re-connection was done by a professional
5) a ready market exists for the old engines (£500to800). So selling the old engine paid for the re-fitting of the new
6) I was surprised how little it cost to ship a complete engine round the country with "palletline"

 

[neilf39]

Was thinking of getting a DV24ME as it would be a slot in replacement. Is heavy compared to other modern engines. Will do the rounds at the boat show. Beta 25 looks a possible, but like the others would need changes to mounts etc.

 

[Moonbeam]

We have a Konsort (purchased in 2011) fitted with a DV24 that was installed in the year 2000. It came with a fairly meagre two blade fixed prop that pushed us along at probably about the same speed you mention (5.5 knots at 2500 rpm).

So after out first season we upgraded to a slightly over propped 2 blade flex-o-fold (Darglow in the UK sorted the spec and supply) and the increase in motoring speed was very noticeable. We easily achieve 5.5 at 2000 rpm and at 2500 rpm we are doing over 6 knots. So just changing your prop to a larger folder, or indeed a larger fixed prop, may help a lot and of course give you faster sailing speeds if you go for a folder.

If you do change the engine.... I'm a huge fan of our DV24, I think you would like it. It's more than enough HP for a Konsort.

Here's a pic of our old prop next to the flexofold
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