retro-fit engine well - advice sought

[dylan winter]

sorry chaps it is a plastic boat

but does anyone have any experience with engine wells - in line with the centre of the boat and ahead of the rudder

one way or another I have had it with inboards and I am considering cutting an outboard well in the slug

under the lovely round hatch in my 18foot 6 inch triple keel mirror offshore

http://www.keepturningleft.co.uk/gal...ales-brochure/


I was going to put one of these in the well

http://www.tohatsu.com/outboards/6_4st.html

can I get away with a short shaft or do I need a long one?

I obviously need to put in some bracing to transmit the forces back to the hull

how do I enure that the engine gets enough air

can I just cut a hole in the bottom of the boat that matches the leg or do I need to make the hole a lot bigger than that?

any suggestions and advice gratefully accepted


Dylan

PS - I do have a bracket on the back of the boat but given that I have taken on some pretty tough bars in the trip so far I am worried about an outboard the transome doing little more than stirring air just when I need it to grip

[TerryLL]

Why not hang that OB on a bracket off the transom?
My experience with wells has not been good. Air starvation, exhaust gassing, sloshing, overtopping.

Outboards are mighty ugly hanging off the transom, but they sure cause fewer problems back there in the open air, and out of the water when not in use.

[NickW]

Dylan

What's wrong with the old old lunger Volvo diesel that was fitted, has it packed up? I know Volvo parts cost an arm and two legs (or should that be two arms and a leg) but surely it would be cheaper to sort out the diesel, not least because of the greater fuel efficiency.

Nick

[dylan winter]

in some ways it has been great

it provides positive power right where I need ti

the rudder really responds well when under power

the engine provides dry heat for winter sailing and lots of electrical power for the batteries

the filming means that I have upwards of 20 camera batteries on board

but....

I have fixed the diesel many times only for the 50 year old installation to find a new way of going wrong

it has cost me 15 weeks of great summer weather so far and around £2,000

the boat only cost £2,000

it has also provided me with some of the most depressing days of my 58 years so far staring down the abysss of that letterbox of a hatch

Volvo have stopped making spares for all sorts of bits

I am planning to sail around the top of scotland - I just cannot imagine the depression of sitting in some scottish harbout knowing that the nearest help is 150 miles away

I have had several fitters look at the engine - they all make their excuses and leave - then don't answer their phones - or put in a fat bill

the last pro who looked at it said that he needed to pull the engine - taking it out and putting it back would cost £1200 - that was before he touched the thing

so I have had it with old diesels

I am planning to keep it going this summer until it breaks and then either dump the boat or cut a hole in it

so..... I am asking around for experience with outboards in wells

[Canoe]

Dylan,

Our Neptun 27 has a 9,9 hp. el. start, remote controlled longshaft highthrust OB in a well, the prop is 30cm dia and just fits through the well, the motor cannot be turned in the well so I steer with the rudder which is no problem, even reversing is quite exact.

We`ve never had any problem with overheating (watercooled), some exhaust gas comes up when reversing but only a short wiff, air starvation is no problem (there is ample passive ventillation from under the motor washboard and cover), the carb. intake is not even 5cm dia. so it`s not a huge area. Even the largest wakes from the power boats don`t cause a problem in the well (I get my knickers twisted but the motor dos`nt miss a beat)

Being closed in the motor is very quiet and can easily be removed for service (try that with a saildrive/fixed shaft!). The only disadvantage compared to a transom mounted motor is that you can`t tilt it when not in use so the prop. is allways rotating but silent.

In your case with the Mirror OS I think you need to be careful not to select a motor that is too weak to move the rather heavy boat and to not go with a too long shaft as you tend to navigate fairly shallow sandy and muddy water which is not all that healthy for the impeller/cooling system.

Hope that helps,

Alan

[dylan winter]

brilliant.....

I am hoping to get the prop to line up with the old inboard prop

how is the plate the outboard is attached to braced back to the rest of the boat

I am assuming I can put enough woodword in to stop the thing from wandering around too much

Dylan

[Canoe]

[QUOTE

I am hoping to get the prop to line up with the old inboard prop

how is the plate the outboard is attached to braced back to the rest of the boat

Dylan[/QUOTE]


Dylan,

the Neptun well is part of the inner shell, it was manufactured that way and could not be retro duplicated on your Mirror OS.
You will need to brace the well in all directions, the OB mount would need really beefy elbows to prevent the well from flexing in any direction. Our motormount is solid hard wood about 4cm thick and, in our case, bolted to 10mm FG laminations.

What you are planning has been done on other boats, I suggest you have a look at other FG boats with motor wells to get an idea of the different designs and adapt one to suit your boat, I know that the Pandora was offered with a well maybe the Sonata too also a lot of "Mainland" European boats have them.

Go for it, it`s got to be better than the old dieselthumper!

Alan

[v10builder1]

dylan,

One big thing - if you go to OB power, you lose the powerful alternator you have with the diesel. This is, in my view, an important safety issue - especially if you are underway at night for very long, as well as a convenience issue, since your boat probably does not have any alternate power.

To TerryLL post, add plugged up cooling water intake screens and the potential for engine damage, and the corrosion effects of continued submersion of aluminum in salt water. You are also putting gasoline on the boat, unacceptable in my opinion.


No one is going to give you a good price for work on the engine in place, because of the cramped location - this has cost you a good bit already. A proper rebuild (this assumes you can locate a first class rebuilder) or a good used engine (gone through a bit to insure you don't continue to have problem after problem) would be the way to go. Maybe you can furnish some/all labor for the removal/replacement to keep cost down. When your engine installation is tight, you should insure that everything is good before replacing the engine in the space.


If you add the cost of the OB engine, the cost of the custom (expensive) well, and the cost of some way to get you a suitable 12 VDC charger (solar, wind generator or gas engine generator or something), you are a way down the road to a rebuild or a used engine - as a plus, no significant changes to the rest of the boat would be needed if you rebuild or replace in kind.

Sail/diesel on.

Joe

[Ron Williamson]

This guy has done a few conversions.
Dig around a bit.
http://atomvoyages.com/articles/impr...utboard-1.html
R

[Gib Etheridge]

I would mount 2 of 2 cylinder remote shift/throttle electric start outboards on the transom and steer with the rudder. 2 cylinder engines run much more smoothly than 1 cylinder engines, 2 outboards provide you with a backup and spare parts, and you can run them both at the same time to keep your center of effort on the centerline. If you ever lose the rudder you can steer by running one engine a bit faster than the other, or even by just running one off center engine at a time, and you can turn on a dime in a tight spot by reversing one and forwarding the other. You can tilt them out of the water when sailing. Electric start engines have high capacity charging systems, and you would have 2 of them. Power tilt would be nice, too.

If I had to install a well on that boat I would get the extra long shaft outboard so as to maintain as much freeboard as possible, 25" from the top of the "transom" to the bottom of the boat at the opening.

I would rip a piece of 5/8 or 3/4 marine ply into 2 of 24" X 96", sandwich them together with epoxy to net 1 1/4 or 1 1/2 thick and fit them in as a forward transom just aft of the aft end of the keel, bedded in thickened epoxy and bonded to the bottom and sides of the hull with progressively narrower strips of glass cloth, kind of a glass reinforced fillet that extends well onto the hull and the forward face of the plywood. This forward transom would be raked back to paralell with the transom, since that looks like about the correct rake for an outboard mount.

Next would be 2 side walls for the well, same thickness and technique and just a bit wider than the space needed to drop the outboard down through. Each of these bulheads would be let into the forward transom 1/4" and bedded in epoxy and lag bolted through the forward and aft transoms. Just outboard of each of these 2 fore and aft running bulkheads I would run 2 or 3 of 1/2" bronze all thread rods from the forward face of the new forward transom through to the after face of the transom, with bronze nuts and fender washers. Tightened these would transfer all of the thrust to the transom and keep the sidewall to transom joints tightly closed.

After that I would let in an after bulkhead between the 2 side bulkheads, same construction and bonding and with 2 more long bolts running athwartships just aft of this new after bulkhead. I would use the lags here as well, just to keep the joints tight while the epoxy cures.

All of this would be assembled as a unit and dropped into place before bonding to the hull, the opening traced onto the bottom, the assembly removed and the hole cut, then reinstalled and bonded and bolted into place.

I would backup the bonding with lag bolts up through the bottom into the edges of the assembly, bedding the bolts in some tenacious adhesive caulk like 5200.

The hole being as small as possible would not allow steering with the tiller, but you could tighten the steering to remain amidships and steer with the rudder.

From there I would cover the 2 large side and 1 small after wells created by the assembly with watertight hatches for storage or floatation.

[CalebD]

You mean gasoline is dangerous?
So I guess my 45 year old gas powered Atomic 4 has been lucky to survive so long?
It still runs more quietly then any diesel engine I have ever met.
I also know how to give it the TLC it does need.

[NickW]

Dylan

Gib's ideas in post 10 would fit the bill nicely. One thing though, having had an old GRP Kingfisher 20 I can tell you that cutting the hole will be a PITA. The layup around the keel area will be anything from 3/4 to 1" + thick and a jigsaw won't have enough guts to cut it. To avoid any stress concentrations at the corners of the well which may lead to cracking of the layup, you'll need to drill say 3" diameter holes at each corner using a hefty low speed drill with tungstun carbide hole cutter then use a circular saw for the straight cuts. With regard to the lag bolts, I'd phone Moray MacPhail at Classic Marine to see if he has any bronze ones.

Nick

[Ron Williamson]

I cut mine out using a regular holesaw then a sawzall.
Nothing special.
R

[seedy]

If you're determined to go OB, sounds like you are, get the longest shaft (cavitation can get expensive), strong alternator, power tilt (and make room to use it). As far as removal, they seem to weigh a lot more when they're down in there. Even though it'll have to be pulled to check/change the lower unit oil, the trim will keep it out of the water when not needed. Yamaha 9.9 is pretty universal, I'd think you could get parts anywhere.

[Slacko]

Get a high thrust prop for it as well.
They are pitched for displacement use, not to make a dinghy fly about the place.
The cavitation problem will go away, and you will get better top speed and punch as well.

[NickW]

Dylan

If you go for the Gib's plan in post 10, you might wish to consider turning the two side wells into dedicated sealed from the rest of the hull storage for bottled gas and petrol. These require to have permentently open drains (ie holes) to allow heavier than air gases and fumes to escape overboard. I don't know how far you intend going into the waterways draining into the Humber estuary but you may be faced with the need to get a Boat Safety Certificate from http://www.boatsafetyscheme.com/site/Home_1.asp .

Nick

[Canoe]

Bump!

Dylan,

did you decide to go for it or did you find an alternative?

Your films are really good, I`d like to buy some, are they available through book shops? (I`ve enquired through your website but got no responce). We`ll be in the UK mid May thru mid June and would like to pick some.

Greetings from Germany,

Alan

[dylan winter]

I would mount 2 of 2 cylinder remote shift/throttle electric start outboards on the transom and steer with the rudder. 2 cylinder engines run much more smoothly than 1 cylinder engines, 2 outboards provide you with a backup and spare parts, and you can run them both at the same time to keep your center of effort on the centerline. If you ever lose the rudder you can steer by running one engine a bit faster than the other, or even by just running one off center engine at a time, and you can turn on a dime in a tight spot by reversing one and forwarding the other. You can tilt them out of the water when sailing. Electric start engines have high capacity charging systems, and you would have 2 of them. Power tilt would be nice, too.

If I had to install a well on that boat I would get the extra long shaft outboard so as to maintain as much freeboard as possible, 25" from the top of the "transom" to the bottom of the boat at the opening.

I would rip a piece of 5/8 or 3/4 marine ply into 2 of 24" X 96", sandwich them together with epoxy to net 1 1/4 or 1 1/2 thick and fit them in as a forward transom just aft of the aft end of the keel, bedded in thickened epoxy and bonded to the bottom and sides of the hull with progressively narrower strips of glass cloth, kind of a glass reinforced fillet that extends well onto the hull and the forward face of the plywood. This forward transom would be raked back to paralell with the transom, since that looks like about the correct rake for an outboard mount.

Next would be 2 side walls for the well, same thickness and technique and just a bit wider than the space needed to drop the outboard down through. Each of these bulheads would be let into the forward transom 1/4" and bedded in epoxy and lag bolted through the forward and aft transoms. Just outboard of each of these 2 fore and aft running bulkheads I would run 2 or 3 of 1/2" bronze all thread rods from the forward face of the new forward transom through to the after face of the transom, with bronze nuts and fender washers. Tightened these would transfer all of the thrust to the transom and keep the sidewall to transom joints tightly closed.

After that I would let in an after bulkhead between the 2 side bulkheads, same construction and bonding and with 2 more long bolts running athwartships just aft of this new after bulkhead. I would use the lags here as well, just to keep the joints tight while the epoxy cures.

All of this would be assembled as a unit and dropped into place before bonding to the hull, the opening traced onto the bottom, the assembly removed and the hole cut, then reinstalled and bonded and bolted into place.

I would backup the bonding with lag bolts up through the bottom into the edges of the assembly, bedding the bolts in some tenacious adhesive caulk like 5200.

The hole being as small as possible would not allow steering with the tiller, but you could tighten the steering to remain amidships and steer with the rudder.

From there I would cover the 2 large side and 1 small after wells created by the assembly with watertight hatches for storage or floatation.

excellent ideas here

I have printed this out and am going to take it with me to see if it works in the boat

thanks very much indeed

d

[dylan winter]

Bump!

Dylan,

did you decide to go for it or did you find an alternative?

Your films are really good, I`d like to buy some, are they available through book shops? (I`ve enquired through your website but got no responce). We`ll be in the UK mid May thru mid June and would like to pick some.

Greetings from Germany,

Alan

sorry allan

all you have to do is to send me an email with your address and I will post some to you

pay once you have them

it is an old system but it works - you should be able to email me direct

http://www.keepturningleft.co.uk/dvd-sets/