hello all (propulsion options for a Relcraft 23)

Hello everyone, this is my first post and im probably saying hello in the wrong area of the forum but if so maybe the mods could move it but i couldnt find where to begin,
at present i have a small displacement type open boat 16' which i use for rod fishing and also laying a few longlines and pots just for myself, not as an occupation, the make is an 'orkney longliner', with a yamaha 9.9 2 stroke outboard, i find it a sturdy little boat but always would have liked something bigger,
Along came an opportunity to acquire a Relcraft 23 hull at a very low price due to circumstances of the last owner who has carried out a lot of work refurbishing it, he hasnt made any drastic changes to the design other than rebuilding the transom which originally had two outdrives for petrol engines, the transom is now completely solid (no holes cut), there is a 90hp 2 stroke yamaha with it and apparently his intentions were to build a platform rear of the stern to hang it from, these Relcraft are classed as a fast cruiser, its a deep 'V' hull 22degree, this one was a customs patrol boat in its youth, i have a ford transit 2.5di engine which i would like to marinise and use and maybe use the 2 stroke yamaha as a 'get home' option if possible, some people tell me i need to use a sterndrive and others say i could use a gearbox and shaft,
there would be flexibility with the position of an inboard engine/beds as the plywood deck is not glassed over yet, im not interested in getting the top speed out of this boat (30 knots apparently) i would be very happy with less than half that with the diesel which i could fuel with agricultural diesel, anyway i will post pics in a couple of days, and i will post my questions in the various areas, thank you, Danno

 

A outdrive puts all the engine weight aft.
Sometimes this is not good.

The beauty of an outdrive is its plug and play installation.
Everything in life is a compromise

 

i cant find any reference to the relcraft 23 on this site but there is info online showing pics at 'relcraft 23, jones's boatyard', if anyone wants to take a look, also i should have said im not a boat designer or an experienced boatbuilder but have some mechanical ability and can also get help with this, basically what i would like you guys to help me with is whatever way to install a diesel inboard and propulsion system and steering that will ,

1. be economical on fuel
2. the easiest system to maintain for a diy man free from complicated electronics etc
3. give a reasonable speed on the water, (just to get me out fishing, no breakneck speeds required/wanted)

my version of the relcraft is the one with the smallest cabin forward and largest cockpit/deck area so theres flexibility with the location of an inboard

also i dont wish to reinvent the wheel here, i dont see any advantage to additions/changes to the hull as im sure hull designers have the best ideas already in there/covered.,
im not one to listen to advise from knowledgable people and then go off and do my own thing especially when we are talking about something as dangerous and powerful as the sea, not to mention wasting my limited funds on something that will turn out to be useless
so i would greatly appreciate the benefit of your advise and years of experience,
thanks in advance, Danno

 

Bracketed Out Board !!

http://www.jonesboatyard.co.uk/documents/Relcraft-23,-26,-29-.pdf

THIS iIS WHAT I FOUND IN A COUPLE OF SHAKES OF A MOUSES TAIL !

Yes a boat that shape and design would lend its self to a bracketed out board about the 90 hp range yamaha is about one of the lightest motors is better to be up in hp than having a small motor sloging its wee heart out from the moment you put it into gear !!
The 90 yamaha is availible in a 25 inch shaft so can get the motor higher up away from the water !! They have trim and tilt at the touch of a button !!
Theres boarding plateform with a single bracket all in one would be ideal for fishing with !! Would give you all that complete cockpit space and no outboard well when you tilt the motor

 

An outboard mounted on a stand off bracket is the cheapest , fastest way to get on the water.

A diesel inboard makes a nice boat...its also expensive and labor intensive to install.

Visit your local marine engine shops and review what used gear they have.

Sometimes you can pick up the pieces required for an inboard installation very cheaply

 

Looking at the 23 footer from the link tunnels put up, I'd say 90 hp is a waste of time. Think 150 would be the minimum, and probably more needed, with 90 you will be going no-where fast with an over-worked engine.

 

Thanks for your replies, yes my boat is the Relcraft 23 in the link that Tunnels put up, its the one with the shortest cabin

As my main prioity is for the boat to be economical (petrol is getting close to Euro 1.70 per Litre over here) i would only wish to use the petrol 90hp outboard as a back up engine to get me home in the event of a breakdown, and as Tunnels says it should be possible to do this by using a bracket or pod off the transom,

As i said i have a diesel ford 2.5 engine from a van, i think they are rated at about 80hp, its a good low mileage engine

i need to know if this engine (marinised) with a gearbox and shaft and prop , would it be suitable in this Relcraft 23 hull and if so how do i determine which gearbox, prop size and pitch and what shaft to use, also what ratio would the gearbox need to be ?, i would be happy with about 15 knots if i could get it as the boat is for fishing not watersports
im aware that the marinising kit and gearbox shaft etc is an expensive option compared to installing an outboard but i would be ok with this if it provided economy with reasonable speed

i have seen an item on the 'lancing marine' website called a transomdrive but its beyond my budget and i think its for use with the engine close to the transom, and as the boat has a lot of space behind the cabin im assuming i could locate the diesel inboard further forward, at present the cockpit area has not been glassed in yet
would appreciate your thoughts and advice on these questions,

thanks, Danno

 

Do the sums on paper !!its your choice at the end of the day !!

Use excel and do a spreed sheet of for and against for each and also running costs etc
YES PETROL is exspensive and like all things keeps going up in price . the installation of a bracketed out board and the extra space in the cockpit is a plus !! the inboard and a marinizing kit for the motor and then a gear box 2-1 probably then the installation of that and all the parts needed then the running costs between diesel and the same with petrol .
An outboard of about the 60 hp range merc called a big foot would be suitable and give you the 15 plus knots you looking at ,but would be a 20 inch not a 25 inch like i suggested .
There fores and against on both sides !!
If you get into full time fishing every day all day traveling long distances then diesel is the way to go but as a partime venture an outboard would always be my choice !!
Also theres the rudder and all the things that go with it !! and in reverse rudders are next to useless till you get moving !!

 

15 knots would be "planing hump" territory for that hull, and in no way an efficient speed for it. I'd say 20knots would have it running cleanly, and 80 or 90 hp is far short of requirements for that. In reality you'd only save fuel with a small engine if you potter around at 5 knots.

 

Once you climb into 100hp plus then the outboard becomes heavy !! i have a 115 hp vee 4 on my14 foot fishing boat, it will do 60 mph but i only get on the plane at 2500rpms and it cruises beautifully at that speed and its really economical to run for long distances !!

 

:?:any further advise out there?;

 

Big beamy boat, weight won't worry it, but it needs horses not ponies.

 

ok if the ford transit 2.5di at around 80hp is not going to be enough for this hull what hp of diesel inboard do you think i would need in this boat or any suggestions as to what engine or setup to use etc, thanks

 

Big Hello, I'm Simon Owner of Relcraft Boaters Group, just found this thread whilst surfing the web, You can find us at
www.RelcraftBoatersGroup.co.uk
Facebook.com/RelcraftBoatersGroup
Twitter : Relcraft_RBG
Email : RelcraftBoatersGroup@Gmail.com

Please feel free to get in touch and I'll do the best to help along with fellow craft owners and Ex employee's of Reliance Marine/Relcraft Marine.

Hope to here from you.

Kind Regards

Simon

 

Engine spec

Just to give you an Idea, If you youtube Relcraft you will see footage of a
23Ft Sapphire out at sea using a 25hp Outboard.

The hull was designed to plain at 11 knots plus (obviously weight depending) so you don't need a lot of power to do this. What application are you using your craft, If your an inland cruiser a 90hp landrover/transit engine will tick along nicely but will have the torque to cope comfortably out at sea.

If I ever get chance to do a hull from new I would fit twin 60hp - 90hp diesel engines. small/compact/eco.