Fitting an inboard to an outboard powered boat?

[Chas78]

Hi All,

As the title says i have a 1987 27ft GRP Highbridge Crusader which i love and is powered by an outboard 15hp Parson 4 stroke petrol engine and although the engine performs well i would really prefer to have an inboard diesel engine fitted. Is this a big job as there seems to be plenty of room around the outboard engine area to fit one and it does look doable it does not have to be a big engine as my boat is pretty light. So if anyone knows of anyone willing to do the job and rough cost or has info on how it can be done or advice on how perhaps i can do the job myself it would very much appreciated thanks in advance

[Alan de Enfield]

Hi All,

As the title says i have a 1987 27ft GRP Highbridge Crusader which i love and is powered by an outboard 15hp Parson 4 stroke petrol engine and although the engine performs well i would really prefer to have an inboard diesel engine fitted. Is this a big job as there seems to be plenty of room around the outboard engine area to fit one and it does look doable it does not have to be a big engine as my boat is pretty light. So if anyone knows of anyone willing to do the job and rough cost or has info on how it can be done or advice on how perhaps i can do the job myself it would very much appreciated thanks in advance

 

Assuming it can be done (and don't forget sticking a big 'lump' in the back will have a big effect on the boat trim) I would hazard a guess that :

 

Engine, wiring, gearbox, shaft and prop would come in at around £2000 + labour.

 

Then :

Where will you put your diesel fuel tank ?

How big a tank can you accommodate ?

More weight at the rear - a 20 gallon tank would be around another 200lbs weight.

Another battery for the 'starter'.

 

I would guess you would be adding around 1/4 of a ton at the back end.

I know Highbridges were built with inboard petrol engines so it can be one, but maybe it needs doing at the manufacturing stage because of various reasons (strengtheners, buoyancy, installation of fuel tank etc)

[Chas78]

Hi,

Thank you for the quick reply wow looking at that lot i think it would be easier to buy a boat with an inboard already fitted i never thought about an extra fuel tank strengtheners buoyancy etc etc doh

[Arthur Brown]

That certainly seems like a lot of serious work, not even knowing that the hull shape will easily let you fit stern tube and A (or P ) brackets.

 

To get the props under the boat at a sensible angle for the prop shaft and gear box you need the engine well forward. Often the space under the centre cockpit is the engine hole. It's a big project. Possibly too big.

 

Look for a boat made that way!

[cereal tiller]

Hi,

Thank you for the quick reply wow looking at that lot i think it would be easier to buy a boat with an inboard already fitted i never thought about an extra fuel tank strengtheners buoyancy etc etc doh

The underwater shape of the Boat would make installing a conventional shaft ,rudder and propeller difficult.

 

Outdrives are best avoided .

 

CT

[Chas78]

Thanks again all but i think this idea will be put to bed and i had to ask the question

[Alan de Enfield]

I have seen them (with petrol inboards) sell at around £7500

 

BUT

 

I'd suggest avoiding Petrol engines full stop.

As you will already be aware, BSS requirements are 'tighter' and the availability of petrol on the cut is not 'wonderful'.

You will have a bigger tank, but will also probably use more, and you will lose the ability to refuel on the bank - you will be committed to pouring Jerry cans into a 'hole in the boat' - spillages and fumes can then settle where we don't want them.

 

Petrol engine boats will always sell at many £1000s below an equivalent diesel engined boat for those very reasons.

[Chas78]

I have seen them (with petrol inboards) sell at around £7500

 

BUT

 

I'd suggest avoiding Petrol engines full stop.

As you will already be aware, BSS requirements are 'tighter' and the availability of petrol on the cut is not 'wonderful'.

You will have a bigger tank, but will also probably use more, and you will lose the ability to refuel on the bank - you will be committed to pouring Jerry cans into a 'hole in the boat' - spillages and fumes can then settle where we don't want them.

 

Petrol engine boats will always sell at many £1000s below an equivalent diesel engined boat for those very reasons.

I agree with everything you are saying yes spillages are frequent trying to juggle with a jerry can also my boat has no charging from the engine or very little oh well my mind is made up i think ;-)

[Arthur Brown]

I you can find an inboard engine boat that's to your liking, then consider retro fitting a diesel.

 

As a total project, fit yourself an outboard rudder with a hydraulic motor and prop, and bring some pipes into the hull to a small diesel which makes hydraulic power and electric power.

[zenataomm]

May I suggest fitting a mast and sail might be easier.

[MtB]

The idea of finding a petrol engined boat cheapo then swapping it for a diesel seems attractive at first sight.

 

Should get a bit of change from about £5k if you if fit a second hand diesel, so maybe just buy a diesel engined boat in the first place...

[Chas78]

Mike this boat came up at the right price at the right time but in hindsight i should have waited and bout a derv powered boat but they are far and few between i think my boat is as close to a Narrowboat as possible but without the price tag with it's 6ft+ headroom outside forward seating area etc etc

[Murflynn]

as long as we are using red diesel it is not DERV.

[Chas78]

as long as we are using red diesel it is not DERV.

You know exactly what i mean !!

[Mendip-Locks]

Here's an option https://www.ebay.co.uk/itm/272350935451ford Desiel in it lowish start price.

Ade