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Islander 28: Atomic 4 Prop Replacement

10K views 23 replies 9 participants last post by  Afterburner 
#1 · (Edited)
Its time to replace our prop. We have a 1978 Islander 28 w/ Atomic 4. It looks to be original-two blade, its getting pink :( , and it has some pitch issues that the original props had. Has any found a replacement prop that they've had good luck with? I've seen discussion on two props that look promising:

CDI: Atomic 4
Indigo: Boat Seem Underpowered?

Also Moyer Marine has some good discussion: Moyer Marine Atomic 4 Engine Rebuilding and Parts

Any input would be greatly appreciated!
 
#2 ·
Get ahold of Norm Ross at WestbyNorth enterprises

West by North Enterprises

He carries a good line of props and provides good service (no affiliation btw) The Campbell Sailor prop is a good lower cost/lower drag alternative to the various folders and feathering props, though he carries several of those as well.
 
#6 ·
We put our boat in the water today and motored to our slip. First impressions of the Indigo prop are very positive! We have tons more forward thrust. It almost feels like we went from a sailboat to a motor boat! The RPMs are higher and the Atomic 4 sounds so much happier and smoother. The other prop really bogged down the engine and didn't allow it to get to top of its performance curve.

More impressions later.

Alan
 
#8 ·
Props for I-28?

I recently changed props on my I-28 when I changed from the original Volvo MD7A to a Yanmar 3YM20. I therefore have two props in very good condition available to anybody with a Volvo-powered I-28 who is willing to pay shipping costs. One of these props is a standard two-blade, the other is a nearly new Campbell Sailor 3-blade prop.
 
#11 ·
Repower of I-28

We had our Volvo MD7A replaced with a Yanmar 3YM20 by a yard in Canada (Canoe Cove, near Sidney, BC). The engine cost about $7,300 CAN and the installation was quite a bit more than this but the yard replaced absolutely everything in the propulsion system - fuel tank, shaft, prop, dripless seal, hoses, water lift muffler and hose, exhaust thru-hull (now 2") and sea strainer. The only items from the original propulsion system are the Raycor primary filter (but its hoses are new) and the fuel deck fill fitting. Because the engine and fuel tank were out of the way, I also had the yard install an electric bilge pump - which turned out to be an expensive job. Install of the eninge alone probably cost about an addtional $5,000 CAN (for this install, they put the engine in place and removed it three times to get the engine bed/motor mounts/transmission aligned correctly to the new shaft, renting a crane for the job each time).
One thing I did just prior to the installation which saved much time and therefore labor expense was to install a relatively large aluminum hatch in the cockpit sole, betweent the area where the engine and fuel tank are located. This saved considerable time during this job and easily paid for itself.
Another thing my wife and I did during the install was to paint the engine compartment. Over a weekend when the engine and fuel tanks were removed, we cleaned up 32 years of oil, grease, etc. and painted the floor of the engine compartment with two coats of Interlux's Bilgekote. We also removed the original black foam souond installation (which was crumbling to dust) and painted the sides of the compartment with several coats of Silent Running's SR1000 which deadens sound equally well to the original foam, is much less expensive and thinner, giving us ca. 1" more room around the engine.
Although this was an expensive project, we use the boat for cruising several weeks as a time in realitively remote areas so we believe the more relaiable engine was worth the time and expense. The new engine has considerably more power and at max rpm (3,600) drives the boat at 6.7 knots which the old Volvo could not. At 80% power, we do just under hull speed (ca. 6.2 knots) with the Yanmar.
 
#12 ·
Thanks for the reply DL. My wife and I were in Sidney a few weeks ago with our boat. We did see a very nice 2I8 while we were there but the owners were not around. It had a brown dodger. It would have been great to be able to talk with you. We spent three weeks in the Gulf Islands and our Volvo barely got us home. We are going to repower our boat starting sometime this month. Hopefully I’ll be able to do a lot of the work myself and save a little money. I am trying to decide between the Yanmar 3YM20 and the Beta Marine 16 or 20 HP models. Did you consider the Beta Marine? Which prop did you use? Is it a two or three blade model? If you have any words of wisdom concerning the install, or any pictures I would love to hear and/or see them. E-mail me if you like.
 
#13 ·
I-28 repower

The Islander 28 with a brown dodger would likely have been our boat, Polaris. We go to Canoe Cove frequently since it is the closest yard to our house. We did consider the Beta Marine engine, but decided to go with Canoe Cove to do the installation (we had considerable work done there previously and were most impressed with the jobs they have done for us) and they are a Yanmar dealer. The prop now on the boat is a Campbell Sailor 3-blade prop, 3/4 X 12d X 11p. Vic prop calculated that the Yanmar 3YM20 should optimally have a 15" prop, but there was not sufficient clearance for this diameter if the prop would be in the same location and moving the prop towards the stern by elongating the shaft might put too much strain on the cutlass bearing due to the small diameter of the shaft. There was some discussion of iincreasing the diameter of the shaft to one 1" so the prop could be moved to the stern, but this seemed to be quite a bit of extra work. They did,however, replace the stock 3/4" shaft with one made of Aquamet 22, a terribly strong and corrosion resistant alloy.
 
#18 ·
Yes, indeed. I have two props which I used on my 1978 Islander 28 witn a Volvo MD7 engine. One is a two blade prop, in very good condition, and a second which is a 3-blade Capbell Sailor prop, which is in nearly new condition. Shortly after I purchased the second prop I changed the engine in my boat to a Yanmar 3YM20 which required a change in prop and shaft because of the increase in hp and direction of operation. I would very much like to find a home for these two propellers.:)
 
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