Replacement for bmw d7 marine... would yanmar ysb8 fit with minimal DIY installation work

[boatguy22]

As per title...
Im looking for a nearish Replacement for a bmw d7 marine... would the yanmar ysb8 fit with minimal DIY installation work

Im not sure how it all goes in relation to engine mountings and prop shaft mountings meeting up in a near equal area.

Any help or tips would be appreciated

Thanks

 

[garymalmgren]

would the yanmar ysb8 fit with minimal DIY installation work

The answer is probably. no.
It is very rare for one engine to easily replace another.
You can take measurements, but in the real world the only way is to remove the old engine, drop the new one in and chop and add until it lines up.
I know it sounds horrible, but with patience, a sabre saw, hardwood and epoxy it can be done.

gary

 

[Thistle]

I replaced a BMW D7 with a Beta 10 without much problem. The main change was extending the engine bearers.

 

[Stemar]

Is it Beta who will make up engine mounts to fit to other engine setups?

Pretty much anything can replace anything - I replaced an MD1 with a VP2003, but I had a competent mechanic to help me (he did the spannery stuff and I passed him tools ), and the companionway steps needed significant surgery.

 

[Tranona]

Likely more than the normal amount of work because of the offset gearbox output. The propshaft coupling is the fixed point so take your measurements from there. EExpect you will need new bearers as other engines have central outputs. The YSB8 is even more agricultural than the Hatz/BMW and you are unlikely to find one in decent condition. The most obvious replacement is a Yanmar 1GM which can be found secondhand in decent condition. However be aware you are likely to spend as much on fitting it as the engine and box will cost. Be aware that modern engines usually run faster than older ones so you will almost certainly need a new propeller. It is the shaft speed that is important so look carefully at the reduction ratio of any replacement engine. There are usually 2 different choices or in the Yanmars 3. You don't say what is wrong with the BMW but if it runs reliably suggest you stick with it. Fitting a replacement engine, even a used one if you can find it is likely to exceed what you paid for the boat.

BTW that is a pretty extreme choice for a first time boater. You may find it more challenging to learn on than a more conventional boat.

 

[LittleSister]

I agree fitting a YSB8 probably unwise due to age (and, I think limited availability of some spares) and impact on resale value compared to something more modern. If you are going to all the trouble and expense of fitting a replacement engine, get something more recent. Consider trying to get the BMW fixed if you need to put off that challenge & expense. Or could the boat be adapted to be outboard powered?

Whatever inboard engine you replace with, you will almost certainly need:
- new 'feet' made to match the engine to the bearers, and/or may need to raise, lower or extend the bearers
- new engine flexible mounts.

You will probably need
- new prop shaft;
- new propellor;
- new exhaust hose;
- new cooling water hose;
- new fuel hose;
- some new wiring.

You may need (e.g. if the hose sizes are different)
- new exhaust hull outlet;
- new cooling water hull inlet.

I am sure there are other things, but probably gives you a general idea.

 

[boatguy22]

I was planning to go go all electric and use a 7hp electric outboard... and have solar and wind turbine.. as im going to completely renovate the boat so it is more to relax on board over the summer rather than sailing.
However this will take some time to get the elctrics and battery bank the way i want it.
I do also have a 9.9hp 2 stroke outboard which its rated for on this tri..

I picked up the new engine today but whether i use it or whether it fits is a different story

The new engine has been completly overhauled but it does look a bit on the tight side... will have a look over the weekend.

It has the rubber engine mounts and brackets on the bottom , exhaust hose , and starts and runs nicely...

If it fits i will most likely have a bar on the gear selector rod to select forward neutral and reverse , as the setup is different that the d7 bmw im pretty sure..

Am i right in thinking that when i take the existing mounts off the boat, and as long as the prop shaft mount lines up , and the mount on the bottom of tbe new engines mountings line up onto the mount holder ledges (sorry i dont know the exact terminology) and the prop rpm of my old bmw d7 is fairly similar to the new one... and all hoses etc are replaced if they dont fit...

I may need to resize the fuel / water tank and pottentially the back side of the stairwell into the cabin, away from the prop shaft side...
But only slightly...

Will need to see how the mounting brackets line up on the existing mount holding platforms...

I got rid of the bmw d7 when i decided to go electric , but thought it wouldnt be a huge challenge to refit this... will see i guess...

If it turns out to be more hassle i can always just sell the new engine on

The existing wiring is already in need of a complete overhaul.. so thats no problem..

And the existing throttle control should be possible to fit on the new engine...

But i will control the gear select with a seperate rod, as the new engine has a gear select rod already and i would just need to extend it a little.

 

[Tranona]

Personally I would not waste any time and money trying to fit that old Yanmar, no matter how "good" it is. The wrong sort of engine for the boat. To check out whether it will fit physically you need to make a jig that is based on the propshaft flange and has the bottom of the mounts in the correct position in 3 dimensions. This is the jig we made for a Beta 30 to determine the modifications to the engine beds which had previously supported a Perkins. The outboard is a far better solution for a boat that will sail so well. As for electric, there is far more involved in going fully electric than you might imagine if you really want to use it as a viable auxiliary when cruising. Solar and wind simply do not yield enough energy to give you any sort of speed or range and the size of battery bank required to store enough energy from shorepower will be both expensive and bulky/heavy.

 

[LittleSister]

The bit that you are pointing at is one of the 'feet'.

Underneath it is an engine mount - these have a rubber body and provide a degree of vibration/noise insulation between the engine and the boat's hull. It also has some type of arrangement on the bolt or stud on top of the rubber body (that bolts to the foot) to fine adjust adjust the height of the engine to align the engine's output shaft with the propellor shaft. It is very important that the engine and shaft are exactly aligned both horizontally and vertically - only a really tiny degree of angle can be tolerated (typically measured in thousands of an inch at the simple coupling which joins the two shafts). (Alignment is a little less critical if you had a flexible type of coupling, which I very much doubt you have or will have room to fit.) Aligning the engine is probably not as simple as you might imagine, and probably best first done by someone experienced, but you'll find old threads threads on the subject on this forum with a search.

The bottom of the engine mount is screwed (big screws!) or bolted to the engine bearers, which are what you call 'engine mount holder ledges' - typically stout wooden or GRP ledges that you bolt the engine to. If you are lucky, these are at such a height and width that any difference can either be built up in wood or GRP or plate metal, or can be accommodated by getting new feet made (most boatyards or marine engineers should be able to do this for you if you give them a drawing of the exact design and dimensions of the feet, or better still if you give them the whole job of installing the engine.


But having typed all that out, I am in agreement with Tranona - I do not think it is worth the hassle and cost with that engine.

It will be much, much simpler and cheaper to fit an outboard bracket (with appropriate backing inside the hull), buy yourself a petrol outboard, and go sailing.

Fitting a replacement inboard probably only really worth bothering with if you are replacing it with an identical engine that's a known goer, or buying a new modern engine (Beta or Nanni 10hp or 14hp for example).

If going down the outboard route, removing the existing inboard will reduce a lot of weight and clutter, and give you some additional storage space.

I also agree with Tranona that an all electric set up is unlikely to be a good choice. In my view it would likely score poorly on functionality, cost-effectiveness and resale value.

To sell your YSB8 you will probably need to find someone who already has one (or a YSE8?) that has died.

 

[boatguy22]

Thanks for the input guys!

Sounds like it will be more work than im willing to take on. All the points have been duly noted.

The electric side of things was because ive currently got about 50kw/h of battery cells, which my thoughts were to use about 10 to 15kw/h of the cells.. which would be in place of the inboard weight... about 100 to 150kg..

use a 800w wind turbine on a scaffold pole where the main mast would go... with it supported by the main mast rigging stays.. its a uk built silent wind turbine thats worth circa £2000 to £3000... and weighs about 18kg

use around 800w of solar on the side floats... flexible panels would be light... or solid panels would be around 50 to 70kg total..

the system could be charged while moving, at anchor or on the mooring... or from shore power ... or a petrol generator empty to full in around 4 hours...

And using a 4000w (7hp) electric outboard engine... would give 3 to 4 hours at full power or 10 to 20 hours at lower power... its an italian outboard worth about £4000.. not cheap chinese rubbish.

The boat already has outboard brackets etc in place already... and i do also own a 9.9hp petrol 2 stroke which the boat was originally designed to use.

Been doing a lot of groundwork into the electric system... but will see which method i use...

I know a tri is for flying... but i got it more for cruising on the lakes... and potentially next year migrate to using the mast and sails instead when i am more confident of the boats size..

Is the new engine not suitable due to the alternator and cylinder being side oriented rather than my old bmw d7 being more symetrically aligned in center? Just trying to fugure out the main reason its not suited for the swapover..

Many thanks

 

[LittleSister]

Is the new engine not suitable due to the alternator and cylinder being side oriented rather than my old bmw d7 being more symetrically aligned in center? Just trying to fugure out the main reason its not suited for the swapover.

It's a lot of work and cost for an engine that is old, for which spares are likely to be a problem, and could well be a deterrent to prospective purchasers when you come to sell the boat on. That you probably don't know really know the condition of the engine, what was really done (and not) and how well, as part of the supposed 'complete overhaul', and how well it runs, adds hugely to the caution. It is a very different proposition to fitting a brand new engine with a warranty.

The unusual configuration of the Yanmar isn't the reason people are advising against doing it: they would say the same for any other engine of similar vintage, unless spares were known to still be readily available and you could be confident of its condition. But, being very different to the BMW might potentially even make it impossible to align it with the prop shaft, depending on the space you have available (hull shape, etc.). It's unlikely, but that could be a fundamental no-go - it really depends on how much and what shape space you have. In order to check you could really do with dimensioned drawings (or lots of very careful measurements) of the two engines, and of your prop shaft position, length, alignment, and relation to those of the the current engine bearers and any bulkheads and any restrictive parts of the hull. Armed with those you have a quite challenging 3 dimensional puzzle to solve, probably best done with the aid of a jig, as Tranona suggests.

No one is saying absolutely don't do it, just strongly cautioning against it because you don't seem to appreciate the amount of cost and work involved for what seems a dubious benefit, especially given your electric outboard ambitions. Many of us on here have got our fingers burnt embarking on boat projects of various kinds over the years, and/or observed newcomers to the forum having bitten off more than they can chew. Sometimes we have to learn from our own mistakes, but it's generally far better to learn from other people's mistakes!

Personally, as you already have an outboard bracket and a petrol outboard, it seems perverse to try to replace the inboard unless you have a drop in replacement or can afford a brand new engine. That you aspire to eventually have an all-electric outboard set up makes it seem madness.

 

[garymalmgren]

Personally I would not waste any time and money trying to fit that old Yanmar, no matter how "good" it is. The wrong sort of engine for the boat.

I think I missed something. What sort of boat are we talking about?
Make?
Model?
Year?
Condition?




gary

 

[Tranona]

Personally I would not waste any time and money trying to fit that old Yanmar, no matter how "good" it is. The wrong sort of engine for the boat.

I think I missed something. What sort of boat are we talking about?
Make?
Model?
Year?
Condition?




gary

See here forums.ybw.com/threads/what-is-this-on-my-trimaran-side-floats.608788/