1992 Sea Ray Sundancer 290 Outboard Conversion Project

[Grubble]

You are ignoring the fact that back then there were no compact diesels with a higher output. 150's were use simply because the next option up was a heavy six cylinder.

But you are still trying to compare the power output of a diesel with that of a petrol and ignoring the torque difference. There is a good reason they don't fit 3.0 petrol engines to these size boats - they aren't big enough for the job.

 

[[2068]]

That would be perfect, and not a mongrel either.

Agree, that D4-260 would be a good choice.

Some people seem determined to avoid anything with a pedigree.
They seem inexplicably drawn towards a mongrel, possibly because it’s uniqueness makes it more interesting.
It always surprised me that Reliant Robins continued to sell for so long.

.

 

[thesaintlyone]

That would be perfect, and not a mongrel either.

A Single conversion??? What would that entail exactly

 

[petem]

A Single conversion??? What would that entail exactly

Filling, strengthening and making good the existing hole in the transom and making a new one for the single drive, I assume. You'd need all the other gubbins to install the engine (controls, instruments, fuel filters, etc, etc) unless they come with it. Don't forget that an EDC throttle, actuator, etc will cost over £2k new so don't underestimate these costs.

It's worth noting that the Sealine S28 (similar size and weight) was offered with a single KAD44 260hp which was the predecessor to the D4-260. Not the fastest boat in the world got got on the place (just about). IMO, this would be a good solution and would result in a saleable boat (a D4 powered one could well make the boat the most desirable example out there).

On the basis of the above a 250hp single outboard won't get the boat on the plane. I'd have thought that a single outboard of at least 300hp would be required to give the same performance. As others have said, this will be a mongrel / unsalable boat but at least the outboard would retain it's value.

 

[Chris_d]

Filling, strengthening and making good the existing hole in the transom and making a new one for the single drive, I assume. You'd need all the other to install the engine (controls, instruments, fuel filters, etc, etc).

It's worth noting that the Sealine S28 (similar size and weight) was offered with a single KAD44 260hp which was the predecessor to the D4-260. Not the fastest boat in the world got got on the place (just about). IMO, this would be a good solution and would result in a saleable boat (a D4 powered one could well make the boat the most desirable example out there).

On the basis of the above a 250hp single outboard won't get the boat on the plane. I'd have thought that a single outboard of at least 300hp would be required to give the same performance. As others have said, this will be a mongrel / unsalable boat but at least the outboard would retain it's value.

+1

I'm sure the OP is going to remind us that he is not interested in resale value etc... but I think he is missing the point that most saleable solution is also the best technical solution :encouragement:

 

[thesaintlyone]

+1

I'm sure the OP is going to remind us that he is not interested in resale value etc... but I think he is missing the point that most saleable solution is also the best technical solution :encouragement:

Yes absolutely ? not hight in the list

But at the same time a single diesel inboard with plenty of tourque and reasonable economy and doesn't cost stupid amounts of money to complete is......

 

[thesaintlyone]

Filling, strengthening and making good the existing hole in the transom and making a new one for the single drive, I assume. You'd need all the other gubbins to install the engine (controls, instruments, fuel filters, etc, etc) unless they come with it. Don't forget that an EDC throttle, actuator, etc will cost over £2k new so don't underestimate these costs.

It's worth noting that the Sealine S28 (similar size and weight) was offered with a single KAD44 260hp which was the predecessor to the D4-260. Not the fastest boat in the world got got on the place (just about). IMO, this would be a good solution and would result in a saleable boat (a D4 powered one could well make the boat the most desirable example out there).

On the basis of the above a 250hp single outboard won't get the boat on the plane. I'd have thought that a single outboard of at least 300hp would be required to give the same performance. As others have said, this will be a mongrel / unsalable boat but at least the outboard would retain it's value.

What is an EDC throttle and would an engine generally come with one. Probably one thing that makes any suggestion doable is that one a suitable plan is in place I can begin the conversion bit by bit. With these engines what would be a suitable outboard to look for ??? ?

 

[petem]

What is an EDC throttle and would an engine generally come with one.

That D4 for £7.5k includes instruments, controls etc so don't worry about my EDC comment. You will however need to budget for £3-4k for an outdrive leg on top (talk to Coastal Rides or ivssmarine).

 

[CLB]

But you are still trying to compare the power output of a diesel with that of a petrol and ignoring the torque difference. There is a good reason they don't fit 3.0 petrol engines to these size boats - they aren't big enough for the job.

I am definitely not ignoring the torque difference. Look back through my posts and you will see I mention it numerous times. The torque charcteristics of a four stroke motor, inboard or outboard, is different to a two stroke outboard, which is again different to a diesel.

Sticking a used single D4 in the boat would of course be preferable, but the op was looking for a cheap option and that is going to cost easily £10k plus. Remember he was originally talking about a pair of old 60's. A single 250 two stroke would be an infinitely better option than that and would, IMHO, give this boat slow planning capability.

 

[LBRodders]

A Single conversion??? What would that entail exactly

About 20k ?

 

[BruceK]

What we are seeing is a lot of different opinions and very little first hand or naval architectural knowledge. The boat was designed with a single V8 or twin V6's of specific type. If you go off piste you are effectively experimenting and there are no hard facts. It could be a very expensive exercise with poor results and possibly dangerous re handling at speed. Or a lot of faff , trial and error with added expense for satisfactory results. If you want to be a trail blazer and have money to throw at it then fine. If you want to plan and budget with precise and known quantities then dont go off piste.
I'm not sure you really know what you want out of the boat yet. To me it seems you bought the boat out of consideration for cheap accommodation which is fine and then started tacking further possibilities and ambitions to it. I think maybe it's time to stand back and re-evaluate what it is you want out of the boat, and what exactly your budget is. Right now the whole ambition just strikes me as a pinata with everybody giving it stick hoping the sweeties land in their lap. Somebody is going to loose an eye.

 

[thesaintlyone]

What we are seeing is a lot of different opinions and very little first hand or naval architectural knowledge. The boat was designed with a single V8 or twin V6's of specific type. If you go off piste you are effectively experimenting and there are no hard facts. It could be a very expensive exercise with poor results and possibly dangerous re handling at speed. Or a lot of faff , trial and error with added expense for satisfactory results. If you want to be a trail blazer and have money to throw at it then fine. If you want to plan and budget with precise and known quantities then dont go off piste.
I'm not sure you really know what you want out of the boat yet. To me it seems you bought the boat out of consideration for cheap accommodation which is fine and then started tacking further possibilities and ambitions to it. I think maybe it's time to stand back and re-evaluate what it is you want out of the boat, and what exactly your budget is. Right now the whole ambition just strikes me as a pinata with everybody giving it stick hoping the sweeties land in their lap. Somebody is going to loose an eye.

The idea of installing a more modern ish diesel in it is an attractive option and one of the options in the original post, although a fair bit of work. However given that I am in no rush to get this boat completed as I'll be making good use of it anyway as a stay aboard accommodation. And for basic River trips at the slow speeds allowed on the upper Medway reaches I am presuming I could mount a simple swim platform bracket from the likes of Panther marine and mount a smallish outboard for not alot of effort or cost as a temporary solution whilst completing the other work.

Correct me if I'm wrong but as you say the boat was designed with a single or twin engine in mind. Therefore apart from weight (which could be countered with more Batteries) installing a single diesel as suggested would not greatly affect the characteristics of the boat as the same Hull was offered with a single albeit bigger engine. And its really just doing everything over time which would make it more affordable.

Just a completely left field question out of curiosity as I came across it in my research I have seen dual Stern drives controlled by one engine are theese actually in production or like electric propulsion a good idea but stupidly expensive and only viable in someones research ?

 

[BruceK]

Somebody else here bought a boat from a dealer that had a single diesel transplant in it. Theoretically on paper every thing should have been peachy and diesel to boot but he had no end of issues and grief over performance. I wont mention names as that is his prerogative if he wants to chip in. But the lesson that is learned is that it is not as easy as it sounds. There is a good reason not to go off piste unless you have solid engineering and naval architectural experience to back you up. The guys on the forum are well meaning and have an absolute wealth of experience but not off piste. Nobody here is going to give you a money back refund on poor advice. If you are hell bent on doing what you are doing then employ the advice of someone with the qualifications to back it up.

 

[thesaintlyone]

Look at this on eBay http://www.ebay.co.uk/itm/370361877989

Re-Powering with a pair of these ?

 

[LBRodders]

Does anyone else get the feeling we are getting troll'ed here...?
Saintly, I think you have been through every option as your preferred choice... twice...?!

It's going to take some coin to make this work and I feel that was never your intention when you spent £5k...

In the words of the dragons 'Im out!'

 

[thesaintlyone]

Does anyone else get the feeling we are getting troll'ed here...?
Saintly, I think you have been through every option as your preferred choice... twice...?!

It's going to take some coin to make this work and I feel that was never your intention when you spent £5k...

In the words of the dragons 'Im out!'

My options are three as said from the beginning I suppose it's the nature of these forums that when a solid idea gets put forward others will debate it and through no fault of their own cause confusion over what works and what doesn't this is not about trolling but getting advice on a suitable Re-Power solution of which I have reccieved loads and am truly grateful.

Take for example the suggestion of a £4000 yamaha 250hp outboard. I like it and in theory it works both financially and practically but then as said by the nature of this forum I get lots of discussion on wether a 250hp two stroke will actually be enough and suddenly I don't know what to do again So do you really blame me if I am confused and not just throwing money at the problem ?

 

[thesaintlyone]

I would add to that I don't have an issue spending the money I just don't have all of it right now and that is the very essence of affordable. Buying a cheaper Base boat and building it up over time to become something enjoyed to the full.

 

[Chris_d]

Look at this on eBay http://www.ebay.co.uk/itm/370361877989

Re-Powering with a pair of these ��

I would refer to my post #1 of your original thread, put back like for like engines and drives. You finally seem to be seeing the sense or you are a troll. But that ebay engine is a bare block you will need to spend that again on marinsing bits, then the same again on outdrives.
Do not understand at all what you are trying to do :ambivalence:

 

[thesaintlyone]

I would refer to my post #1 of your original thread, put back like for like engines and drives. You finally seem to be seeing the sense or you are a troll. But that ebay engine is a bare block you will need to spend that again on marinsing bits, then the same again on outdrives.
Do not understand at all what you are trying to do :ambivalence:

Put an engine/engines in a boat and make it go forward. As affordable as possible and note I don't say cheap as possible!!!! There is a big difference

My biggest concern with like for like is a) sourcing a pair of engines and B) knowing that those engines are not just someone else's crap because that's just buying problems down the line which is why an outboard is the most attractive option to me as they can be swapped out easy if they go wrong ?

 

[CLB]

I give the saint the benefit of the doubt. It's a tough call. What you are proposing to do it difficult, especially if you want to keep costs down. The best option is of course a pair of brand new diesels, maybe a couple of D3 220hp. Next comes a nice big single diesel, ideally of around 300hp. Then you have the option of a couple of replacement petrol motors and drives, or even one big single petrol. ALl the above range from £40k+ to maybe £6k for a used big single petrol with drive. The last resort, in my opinion, is to convert to outboard, but if you do then I think the best option is one big single, rather than a pair of smaller units. It will be easier to source and offer better performance for the same HP. The only reason I can see for going the outboard route is cost and at £4k that Yamaha is about as good as it gets. Whatever way you go, you are looking at an absolute minimum of £5k to make this boat go fast again. The upper limit will be getting on for £50K. In reality, you paid £5k for the boat, so spending another £5-£10K on it is perhaps as much as should be considered worthwhile. If you go outboard, you want to be at the bottom end of that £5-10K, but if you go inboard diesel you could happily be at the top end. The rest is really down to you. Will a single 250hp be enough. In truth, no-one s going to give you a definite answer. I think yes, others say no. I have re-engined boats myself, and I have been involved with other people's re-engine projects, including inboard to outboard, but even so, no one ever really knew how the boat was going to perform until the job was completed and the boat back in the water.

The only other option is to forget going fast, stick to the river and bolts an outboard of up to 50hp on the transom. Anything in between is a waste of time, money and horse power.