Possible replacement for a Volvo MD11B(C)

croc9968

croc9968

Member
Joined
5 Mar 2020
Messages
41
Location
Seaham
Visit site
I have the original 1984 Volvo MD11 in my Maxi 100 and I'm looking to upgrade to a newer engine. There have been a few previous topics similar to this and some have suggested the Volvo D1-30 or Beta 20/25. The peculiar thing about the Maxi 100 and 95 are that the engines are mounted under the cabin table which is excellent for accessibility but reduces choice somewhat as the MD11 is narrow. The drivetrain is not a sail drive so I guess mounts would be fairly universally spaced?

I would welcome advise or recommendations though.

1616683631827.png
 
Mount spacing on modern engines are generally narrower than older engines. D1 30 and Beta 28 centres are 410mm, overall engine widths Volvo 482mm Beta 496mm overall length Volvo 728mm Beta 779mm. I would be very surprised if they are larger than the MD11. Both engines are commonly used as replacements but will require modifications to the engine beds because the mounts are at different centres and heights relative to the propshaft flange. Beta will supply custom made engine feet to go direct onto your existing beds and any competent installer could do the same for the Volvo. You will need to consider at least a new propeller and may well find other items such as controls, exhaust fuel supply that need modifying and other items replaced because they are old and worn out.

The cost is significant, particularly if you have it done professionally, but the functional benefits are well worth it in terms of refinement and potential long term low running costs. Unless it is a distress purchase you need to be prepared to keep the boat for some time to get some return as the short term value of the boat will rise far less than the cost of the new engine.
 
I wouldn't have thought you would have trouble replacing it with beta 25, the betas quite a bit smaller and lighter. 247kg to 113 kg! google tells me.

As Tranona says beta will do you custom feet, saves a lot of time and faff if you haven't got the fabrication skills yourself.

Shaft coupling might also be different - and you may need a slightly longer shaft as the overall length is shorter on the beta.

As you say access is great, so it shouldn't be too painful except for the stuff mentioned previously.

You could always make yourself a carboard template once your old lumps out of the way before you commit!

MD 11 Dimentions Product Bulletin (maritimepropulsion.com)

Beta 25 Dimentions B25 HE DataSheet REV 04 0121

I make them the same width, The MD11 being a little asymmetric but i'm pretty sure your table is square in the maxi ....its been a while.
 
croc9968 said:
Thank you for your replies so far
Click to expand...


Make sure when talking to Beta you not only discuss the custom mounting feet but also discuss the high rise exhaust elbow and the higher power alternator options. Note the the drive from the Beta is in the opposite direction to a Volvo so you may need a new right hand propeller.

On a boat such as yours I would definitely go for the high rise exhaust in order to reduce the chance of back flooding from the exhaust into the engine. I never cease to be surprised at the number of re engine installations that have failed due to this problem which goes on to cause slow deterioration of the valve seats on the rear and possibly other cylinders. I think Beta would recommend it for your boat.
 
The MD11 has a large flywheel at the front 1= which is usually outside the bearers and is tall slim engine
But modern units have a smaller lighter flywheel in the middle and are relatively low and squat which requires wider bearers so you are going to have to alter the bearers Beta have a good track record in this respect so definitely worth speaking to
 
The D1 30 and the Beta 28 have the same lateral mount centres (410mm) but the smaller Beta 25 is actually narrower at 370mm. So the first 2 will fit on the existing bearers widthwise and the 25 will need extending inwards. Suspect all will have different heights from mounts to output coupling centre and the existing engine may well have a 7 degree down angle gearbox., so height and angle may need to be changed either by adapting brackets of modifying the bearers to suit. The Beta is available with a 7 degree down angle box, but with different reduction ratios from the standard box. Care is needed to make the right choice of reduction ratio and propeller size to suit the boat.
 
The prop issue is one that has puzzled me. I replaced my Volvo 2003 with a Beta 30 and had to change the prop for a RH one. I was told at the time that the Volvo D 1-30 also required a RH prop. Now the Beta engine rotates in the conventional direction (clockwise as viewed from the front) but the gearbox changes the direction when set in the "forward" direction. Why could I not just have set the gear selection to operate the other way so that the forward selection resulted in clockwise prop rotation as viewed from ahead and my old LH prop would have worked?
 
Quite simple for 2 reasons. First the box is not rated for continuous running in reverse gear and second the reverse gear ratio is likely to be different from the forward. There are gearboxes that do allow continuous running in either direction but the standard TMC gearbox is not one of them.
 
Bodach na mara said:
The prop issue is one that has puzzled me. I replaced my Volvo 2003 with a Beta 30 and had to change the prop for a RH one. I was told at the time that the Volvo D 1-30 also required a RH prop. Now the Beta engine rotates in the conventional direction (clockwise as viewed from the front) but the gearbox changes the direction when set in the "forward" direction. Why could I not just have set the gear selection to operate the other way so that the forward selection resulted in clockwise prop rotation as viewed from ahead and my old LH prop would have worked?
Click to expand...
Some gearboxes are ok ie but others have different gear trains and ratios and oil supplies
 
scottie said:
The MD11 has a large flywheel at the front 1= which is usually outside the bearers and is tall slim engine
But modern units have a smaller lighter flywheel in the middle and are relatively low and squat which requires wider bearers so you are going to have to alter the bearers Beta have a good track record in this respect so definitely worth speaking to
Click to expand...

No problem with Beta. The engine will sit in position and Beta sell custom engine mounts to suite the narrower beds.
 
jwfrary said:
According to the website no beta 28.... 25 or 30. 25 More than adequate in my opinion.
Click to expand...
Yes, I know, but I still had the old 28 in my file of engines details from an old project. Same basic engine and physical dimensions, just a slightly bigger capacity in the 30hp version. Bit better packaged with the later alternator which reduces the width.
 
I am looking at replacing my volvo with Yanmar 3YM30E (I am not 100% sure this will fit under the table), the Beta 25 but this needs a new prop and shaft and I am stuck in a marina so installation needs to be at a quayside so not sure if replacing the shaft and prop is possible there and Vetus M3.29 but this also looks a little too big for the space under the table. Can anyone help me choose with certainty? Has anyone tried the Vetus? The Yanmar?
 
Helen Adams said:
I am looking at replacing my volvo with Yanmar 3YM30E (I am not 100% sure this will fit under the table), the Beta 25 but this needs a new prop and shaft and I am stuck in a marina so installation needs to be at a quayside so not sure if replacing the shaft and prop is possible there and Vetus M3.29 but this also looks a little too big for the space under the table. Can anyone help me choose with certainty? Has anyone tried the Vetus? The Yanmar?
Click to expand...
Welcome.

You don't say what boat you have nor exactly which model Volvo. Is it the same Maxi 100 and MD11 as the original poster? I think you will find that you need a new propeller for any of the latest engines compared with an old Volvo, not just because most turn in the opposite direction with the normal mechanical gearboxes, but the power and shaft speed will likely be different. You may not need to change the shaft depending on its condition and whether the length is suitable - that is the coupling on the new engine will be in exactly the same position as the existing. You will have to change the coupling on the shaft to match that on the new engine. All the new engines are substantially shorter and lower, but may be a bit wider. Almost certainly you will have to modify the engine beds or have brackets made up to deal with different heights and possibly width. Mount centres differ - the Beta 30 is the same, Beta 25 is narrower. You may well have to re-arrange the exhaust system because the outlet on most engines is now on the starboard side looking aft whereas older Volvos (including the MD11) it is on the opposite side.

Which of the different makes you choose will depend on a number of factors. First is power output. If your boat is that Maxi then it needs 25hp to achieve hull speed. Most makers offer only a 20hp which is too small or a notionally 30hp (actually 29 for Beta, Volvo, Yanmar or 27 Vetus and Sole) only Beta offer a 25hp. Other factors that influence choice are around location and accessibility of service points, but that may well not be an issue for you.

On balance (for that boat) the Beta 25 is probably the best choice, although some may be tempted by a 30 because it allows cruising at lower rpm without any penalty in fuel consumption. One thing is certain - this is not a job that can be done while still afloat - although much of the preparation can be done beforehand right up to lifting the engine out. However you need to fit a new propeller at least and check the cutless bearing at the outboard end. If you are unsure about what is involved then it makes sense to have the engine professionally installed. You can save money by doing prep work such as dismantling things and cleaning up yourself. That is what I did with my recent re-engine with a Beta 30 - even though I have done 2 similar jobs in the past. I agreed with the installer exactly which each of was responsible for and saved probably £500 in labour while still getting a professional installation to a high standard.

Hope this helps.

Just found this scotland.boatshed.com/maxi_100_ps-boat-247700.html#boatmedia-93 showing a Beta 30 with a PRM box in a Maxi 100. As you see more than enough room. Very neat installation
 
Last edited:
Tranona said:
Welcome.

You don't say what boat you have nor exactly which model Volvo. Is it the same Maxi 100 and MD11 as the original poster? I think you will find that you need a new propeller for any of the latest engines compared with an old Volvo, not just because most turn in the opposite direction with the normal mechanical gearboxes, but the power and shaft speed will likely be different. You may not need to change the shaft depending on its condition and whether the length is suitable - that is the coupling on the new engine will be in exactly the same position as the existing. You will have to change the coupling on the shaft to match that on the new engine. All the new engines are substantially shorter and lower, but may be a bit wider. Almost certainly you will have to modify the engine beds or have brackets made up to deal with different heights and possibly width. Mount centres differ - the Beta 30 is the same, Beta 25 is narrower. You may well have to re-arrange the exhaust system because the outlet on most engines is now on the starboard side looking aft whereas older Volvos (including the MD11) it is on the opposite side.

Which of the different makes you choose will depend on a number of factors. First is power output. If your boat is that Maxi then it needs 25hp to achieve hull speed. Most makers offer only a 20hp which is too small or a notionally 30hp (actually 29 for Beta, Volvo, Yanmar or 27 Vetus and Sole) only Beta offer a 25hp. Other factors that influence choice are around location and accessibility of service points, but that may well not be an issue for you.

On balance (for that boat) the Beta 25 is probably the best choice, although some may be tempted by a 30 because it allows cruising at lower rpm without any penalty in fuel consumption. One thing is certain - this is not a job that can be done while still afloat - although much of the preparation can be done beforehand right up to lifting the engine out. However you need to fit a new propeller at least and check the cutless bearing at the outboard end. If you are unsure about what is involved then it makes sense to have the engine professionally installed. You can save money by doing prep work such as dismantling things and cleaning up yourself. That is what I did with my recent re-engine with a Beta 30 - even though I have done 2 similar jobs in the past. I agreed with the installer exactly which each of was responsible for and saved probably £500 in labour while still getting a professional installation to a high standard.

Hope this helps.

Just found this scotland.boatshed.com/maxi_100_ps-boat-247700.html#boatmedia-93 showing a Beta 30 with a PRM box in a Maxi 100. As you see more than enough room. Very neat installation
Click to expand...
Thank you. I have a maxi 95.
 
You must log in or register to reply here.

Share this page

Top