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Inboard out of my RL 28
I am thinling of changing my 20 hp Bukh inboard to a 4stroke outboard. has any one done this. Cut outs and outboard mount could be the main problem.
P Taylor25-Jun-2005    Edit    Delete 
Re: Inboard out of my RL 28
I can't advise on the finer pionts of the RL28 but I did re-install the well to my RL24 which was pretty easy.

INMA had been a racing yacht with the long shaft outboard on an adjustable stern bracket. The well was sealed with the cockpit drains piped through the empty well.

After looking at a few RL24 wells I determined the shape of the original cutout. Once I had figured out the cutout neaded to be extended back towards the stern and that I needed a short shaft outboard with minimal length I had enough information to go ahead.

I decided that I would not close the well off when the engine was up so cutting the hole was simply marking the shape with tape, drilling the corners with a hole saw and cutting the straight bits with a jig saw. A reciprocating saw would be more suitable for the straight bits because it was slow going with the jig saw. The fibreglass wears the teeth pretty quickly so some spare blades may be needed.

Sealing the cut edge was simply done with some epoxy.

I added some extra layers of fibreglass to the engine mounting pad because the drain holes for the cockpit were larger than standard and had reduced the strength of the original engine mounting pad.

The trapped exhaust gasses in the well can effect the idling of the engine at low speeds. Some manufacturers have exhaust adaptors that screw into the upper exhaust port and provide a hose connection for the exhaust so it can be piped out of the well. My Magnum with a Yamaha outboard had a plastic pipe taking the exhaust out of the well.

I put a new 5hp 2 stroke engine in my new well, took the old outboard off the back and am very happy with the result. Note be sure you get an outboard with a high thrust propellor with high thrust in reverse.

One thing I can say about tilting the outboard, the reduced drag is very noticable, the handling of INMA improves with the engine up. I might make a trapdoor to close the well one day, its probably worthwhile even for a cruiser like me.

One thing I did have to do after trialling the engine was to cut the front of the opening out further so I could tilt the leg down further. I found the outboard could cavitate on steep waves at more than 3/4 throttle. Tilting the outboard seems to have solved the problem. The outboard still cavitates sometimes but it is now generally in waves with a couple of people on the foredeck. I have motored into 25 knots on Port Phillip Bay at about 3 knots at 3/4 throttle. Any faster and the hull was pounding, there was no shortage of thrust and operating the outboard using its tiller controls is so easy. INMA does hull speed (6.5 knots) at 3/4 throttle on flat water.

You may need to measure your well and figure out which outboards suit your yacht. Although all outboards are similar when down and its just long or short shaft for the depth. They have different pivot pionts and propeller sizes which effect the room needed when tilting the outboard. My large diameter high thrust prop only just fits throught the width and length of the RL24 well. The engine cowling needs to miss the tiller when tilting, some brands are higher than others due to the top mounted starters. You may find you need to select a brand and size to convieniently fit in the well.

INMA has two bouyancy tanks in the sides of her well that provide a good platform to sit the outboard fuel tanks. I generally use the standard 12 liter tank and take a 9 liter plastic jerry can for refuelling. For longer cruises I have a 20 liter stainless tank and can take other jerry cans making up to 50 liters stored in the well.

Fuel consumption is an issue. In flat conditions INMA cruises at 5 knots at 1/2 throttle using 1 liter an hour at a guess. On that trip mentioned earlier into 25 knot winds at 3 knots, INMA used 3 liters an hour at a guess. Clearly my range when cruising varies a lot and depends on the conditions.

Now a comment on the power needed for the outboard. Different people told me I should get outboards from 6hp to 15hp for my little RL24. Having raced keel boats with 6hp outboards I knew even heavy yachts are fine with small outboards.

As it happened the only new outboards that would fit in the well were 5hp and the Mariner 2 stroke was my choise with its high thrust propeller. It is noisy because its a single cylinder and works pretty hard, I cope with that.

I am not a great believer in having more power than needed in a yacht. Marine engines (including outboards) need to work hard to keep in good shape, little outboards last longer at flat out or close to flat out where they were designed to run. Running a big outboard at low loads all its life is not good for its life. All that said I can appreciate why people want extra power so they can cruise at slower engine speeds (lower noise) push into headwinds easily, tow a dingy, cross bars safely and stop faster. When deciding the size of outboard all these factors need to be balanced.

I had a Magnum 8.5 with a 10hp Yamaha high thrust 4 stroke, that was more than enough power for yachts like the RL28. There were many Magnums with 8hp outboards which was plenty of power to keep them safe and push them at hull speed.

greg25-Jun-2005    Edit    Delete 
Re: Inboard out of my RL 28
Dear Greg,
You said that INMA has two bouyancy tanks in the sides of her well that provide a good platform to sit the outboard fuel tanks.
AWOL has had engine well modifications resulting in the vertical well sides being about 9 inches high. This allows water to splash up the well and into the two sides formed by the aft locker wall, the hull and well wall. Consequently a thru hull drain hole was added to each side thus these sides always contain various amounts of water depending upon the point of sail.
I've always been conscious of the wasted space in these two side areas. However because these areas are always wet I've been reluctant to store fuel in them for fear of water contamination.
Your setup sounds like a flat floor has been installed to keep everything high and dry and/or that your well sides are high enough to prevent water ingress. Or is it that you have pumped foam into the sides?
Any further comment would be appreciated Greg.
Best wishes,
Toyota Landcruiser HJ45

Terry Stannus27-Jun-2005    Edit    Delete 
Re: Inboard out of my RL 28
Terry your correct in that INMA's tanks have flat tops that act as excellent shelves to sit tanks and the rubbish bag.

The tanks do leak letting water in which is annoying because they are generally above the waterline. I ended up installing the rubber self drainer things in the bottoms of the tanks so any water that might leak in gets drained while on the windward side. It works for me.

greg28-Jun-2005    Edit    Delete 
Re: Inboard out of my RL 28
Having done a lot of cruiseing in the company of other trailer sailers fitted with outboard motors I would stay with the Bukh diesel because of reliability, fuel economy, safer fuel,the engine acts as extra ballast. We have a 20 h.p. Volvo 3 cylinder diesel in our RL28 Rings-n-Things and I have never regretted the decision to re engine with a larger diesel motor.

Kingsley & Kay White

Kingsley White1-Jul-2005    Edit    Delete 
Re: Inboard out of my RL 28
Thanks Kingsley.
My main concern is noise and smell, We motor for at least 6 hours going to the Myall lakes.
P Taylor1-Jul-2005    Edit    Delete 
Re: Inboard out of my RL 28
with outboard in the covered well of the Magnum, noise was not an issue and having two remote petrol tanks seemed easier than diesels filling up at the dock.

In over 20 years sailing with outboards in and out of wells I have never had a failure that stopped the outboard from being able to get us home. I have seen diesels fail due to algae in the fuel a couple of times and seen diesels fail when rough conditions stirred up the rubbish in the bottom of the tank.

As for noise I have one of the noisiest outboards currently sold in the well of my RL24 and do notice it on long trips motoring. Fortunately I have a tillerpilot and am able to move forward away from the noise. I should have bought a tillerpilot with a remote control so I can steer from the companionway or the front of the cockpit.

I am not sure how anyone can suggest a diesel is not noisy, my limited experience has been the noise from the diesel can be very annoying below. At the tiller the diesel might be bearable but most yachts get annoying after a few hours on the engine regardless of whether its a diesel or petrol outboard.

I know people who have used their dingy outboard on their regular outboard bracket when they have had a problem with their main outboard. Its hard to do that with a diesel for any length of time.

greg2-Jul-2005    Edit    Delete 
Re: Inboard out of my RL 28
Everything you say is exactly why I am considering the change to an outboard Greg
P Taylor3-Jul-2005    Edit    Delete 
Re: Inboard out of my RL 28
Our 2020 Volvo Saildrive is both smooth and quiet. We reduced the noise level even further by fitting a paper element type after market aircleaner. I can not recall haveing been bothered or even aware of diesel fumes. Excessive fumes or smell usually indicates a worn out motor or dirty injectors. We cruise at close to seven knots at 2800 rpm using 2.5 litres an hour.

Kay & Kingsley
Kingsley White11-Jul-2005    Edit    Delete 
Re: Inboard out of my RL 28
We have an RL 28 based in Port Stephens that has an 15hp 2 stroke outboard attached. This boat is to survey and does the trip to the Myall weekly for charterers. You are most welcome to see how this system is mounted. We have two 25l Stainless Fuel tanks mounted behind the wet lockers.

Mounts and equipment supplied in the Port Stephens area.

Being a fan of Diesel (being a cheap form of fuel in every part of the world except Australia) given the chance to choose, I would take the Diesel over Petrol as the slow passage to the Myall (4 to 8 Knotts) for many hours, seems to put a fair strain on the 2 stroke that works best at 50 - 75 % power. A Four stroke may be different..

Further you mentioned HP rating. Given that I have been called many times to "Rescue" our boats towards the end of a charter where the users needed to travel across Port Stephens going head into a southerly. Under these conditions "Polaris" was in her element as far as the chop was concerned, however the extra power of the 15 as opposed to a 6 or 8 Hp was of benefit. With the high profile of the boat, we needed all that the 15HP could offer.

If you want to have a look see at how this has been done on Polaris,
please forward an e-mail to auramistlodge@cnn.net.au so we can arrange a time.


Rob Roseworne

Rob Roseworne13-Jul-2005    Edit    Delete 
Re: Inboard out of my RL 28
Greg I am not suggesting it is quiet I can assure you that it is perhaps when we meet on the water You may care to come on board and experience why a properly installed, economical, reliable, modern diesel saildrive is so pleasant to live with.
Kingsley White20-Jul-2005    Edit    Delete 

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