Re-design of 8 Foot Dinghy . . .

[HelmutSheina]

Yes, I had a red-banded (1969) Mercury 7.5 for about 15 years, but the salt water finally did it in. I found a mildly used 1972 7.5 hp for $175 to replace it. On the 1969, I had swapped out the original LU/driveshaft for one from a 1980 motor (then a stainless steel shaft). I brought the shaft/LU over to the 1972.

Not sure if you remember, but in the 1971-72 era Mercury was migrating to a CD type of ignition, and their interim step was known as the 'Phase-Maker' ignition system (a complete piece of crap). Although I could get spark, it was not reliable at all . . . and not for lack of effort on my part. I took the magneto ignition from the 1969 model and installed it on the 1972, scrapping the Phase-Maker. The engine works pretty well.

My next stop on the Mercury food-chain may be a 1980's version . I do have an Evinrude 6HP as a back-up, and a Johnson 4.5HP long shaft for the sailboat. I tend to look for vintage motors in the lower HP range, because they had twin cylinders vs. what you see today. IMO, a single cylinder boat motor is not worth having. I had a friend's 1992 3HP Yamaha for a while . . . single cylinder . . .it never ran well. I gave it back a couple of years ago.

Both Mercury and OMC had some horrible ignition systems, and the old points and condensers were not that bad, just a bit sedate. Some of the OMC V4s had adjustable air gaps on the triggers and ran horribly as the gap increased, while the later potted ones very rarely failed.

Just before I retired a guy brought a cat in with twin V6 FICHTs on it, one not running. Put it on the diagnostic computer and it turned out to be the brain. 15 years ago a computer module was listed at $5000 in AUD. Anyway he bit the bullet and we fitted a new one only for the other engine to fail three months later, and they halved the price on the spot after he gave them a serve. Programmed obsolescence is highly accurate now in the computer age and most insidious.

I have to agree on single cylinder 2 strokes, the only one that was any good was the Tohatsus that both American brands sold.

I have owned two single cylinder 4 strokes and they have been reliable and economical, though not well balanced and vibrate. One is a 2.6 Parsun Chinese motor and it is great, the other was a 6hp Tohatsu Sail Pro that was amazing moved a boat generally needing a 15hp, on very little fuel. It was on a 30' Tiki catamaran and she'd do about 6kn flat out, but the sweet spot was about 4kn.

The two cylinder Mercury 18-25hp XD series ran the prototype of the throttle shift and were horrible motors. I got stuck on a fairly new one at the local port authority that was losing power intermittently. Turned out to be a mild steel exhaust tube under the powerhead had rusted off and was blocking the exhaust lower down. They went to Yamaha after that and I picked up a dealership because of it.

Have enjoyed following the huge modification you have done such a great job of thanks, you can enjoy your boating having no bellows, uni joints, gimbal bearings, manifolds & elbows, to frown over, and the rest of that SD crap that earned me the nickname "The Grim Reaper".

 

[montero]

Both Mercury and OMC had some horrible ignition systems, and the old points and condensers were not that bad, just a bit sedate. Some of the OMC V4s had adjustable air gaps on the triggers and ran horribly as the gap increased, while the later potted ones very rarely failed.

Just before I retired a guy brought a cat in with twin V6 FICHTs on it, one not running. Put it on the diagnostic computer and it turned out to be the brain. 15 years ago a computer module was listed at $5000 in AUD. Anyway he bit the bullet and we fitted a new one only for the other engine to fail three months later, and they halved the price on the spot after he gave them a serve. Programmed obsolescence is highly accurate now in the computer age and most insidious.

I have to agree on single cylinder 2 strokes, the only one that was any good was the Tohatsus that both American brands sold.

I have owned two single cylinder 4 strokes and they have been reliable and economical, though not well balanced and vibrate. One is a 2.6 Parsun Chinese motor and it is great, the other was a 6hp Tohatsu Sail Pro that was amazing moved a boat generally needing a 15hp, on very little fuel. It was on a 30' Tiki catamaran and she'd do about 6kn flat out, but the sweet spot was about 4kn.

The two cylinder Mercury 18-25hp XD series ran the prototype of the throttle shift and were horrible motors. I got stuck on a fairly new one at the local port authority that was losing power intermittently. Turned out to be a mild steel exhaust tube under the powerhead had rusted off and was blocking the exhaust lower down. They went to Yamaha after that and I picked up a dealership because of it.

Have enjoyed following the huge modification you have done such a great job of thanks, you can enjoy your boating having no bellows, uni joints, gimbal bearings, manifolds & elbows, to frown over, and the rest of that SD crap that earned me the nickname "The Grim Reaper".

That first description refers to a very old story. But I know what you're talking about.
Ficht tech kill the OMC.
Single cyl. 2T outboard is bad engeneering.
Single cyl. 4T outboard is : I don't know. As a motorcycle engine working well.
Two cylinder Merc : I never touched it
I have a 75 hp 2-stroke Mercury and I don't know what to do with it.

 

[HelmutSheina]

The 75 & 90 3cyl Mercurys were tough outboards outside of a couple of issues. And yes the FICHT was better known as FUCHT.

 

[bajansailor]

Ted, what are your thoughts regarding this little catamaran tender in the post below?
She weighs just over 100 lbs, and her deck is self draining, so no worries about rain water filling her up at the dock.

S

Post in thread 'Ply or foam cat inspired by 3m inflatables'

Wednesday at 6:40 AM

Mate i would plumb your bows a fair bit to give yourself a bit more waterline, makes a huge difference in a small boat. Here's a link to my dinghy, you can see what I mean about the plumb bow. Bridgedeck clearance will give you both self draining and a better ride in rough conditions.

• sailhand

• 

 

[tpenfield]

@bajansailor - Very cool. . . . it gives me some ideas.

 

[ondarvr]

8' Livingston.

A cat with partially sealed hulls, each end, they are used as floatation. Sealing off the rest of each hull at the correct hight would allow for self draining. 90% of the hull is one mat and one roving thick.

These have been built for many decades in the NW, they are everywhere. I have two.

These pics are not of mine.