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johnyjackson 09-12-2011 12:43 PM

Islander 30 MK II Prop Pitch
I recently took out my Atomic 4 and put in a Beta Marine 14. I currently am using a 16 X10 prop, but it is apparent it is the wrong pitch. 16 X 7 has been recommend as has 15 X 8 as "better." Can anyone tell me if they have an I 30 MK II with a Beta 14, what prop pitch is being used.

Thanks JYJ

kentg 09-13-2011 08:13 AM

not sure about the pitch, but am looking to repower with the Beta 16. Did you do the install yourself? How is the fit? Anything I should know from your experience?


Bahama 30 Jazzed

johnyjackson 09-13-2011 12:57 PM

I repowered with a Beta 14 (13.5 hp). I did not do it myself. The mechanic cost was almost the same amount as the basic engine. If course that included cleaning the fuel tank, a new prop shaft, new prop, etc. There is no way in the world I would under take all that. He had to put is some 2 X 2's or about that size on the original motor mounts to get the pan up high enough. Even with the higher engine mounts there was enough room under the cockpit for everything to fit. I don't know the dimensions of the 16, and am not sure you need an engine that big.

I fugure that the new engine, plus installation is almost the curent price of the boat. Oh Well, the Islander has served us well of 25 plus year (we are the second owner and knew the first owner) and hopefully will continue to do so for may more years.

The one problem is the prop pitch. It is obvious that it is wrong, and everyone's "best guess" is a 16 X 7, but the frist "best guress" was 16 X 10.

Hope this helps qith the installation question.

dacap06 09-13-2011 09:56 PM


Originally Posted by johnyjackson (Post 774049)
The one problem is the prop pitch. It is obvious that it is wrong, and everyone's "best guess" is a 16 X 7, but the frist "best guress" was 16 X 10.

For what it is worth to you, Tranquility Base has a Yanmar 2GMF, a 13 HP engine (15 when running flat out). Apparently this engine was an option in 1984 for the Islander Bahama 30. The Island 30 Mk I and II and the Bahama 30 all have the same hull. TB has a 13 x10 R.H. 2 blade prop (most Yanmars are RH engines). The prop seems to me to be about right or is just a smidge underpropped. Unloaded RPM is 3600 rpm. In forward I get up to about 3400 rpm and 6.3 kts or so; hull speed is around 6.68 kts so it is close.

kentg 09-14-2011 07:58 AM

Thanks, the 14 and 16 have almost the same dimentions. I am going to do most of the install myself and save a few bucks. I will replace the fuel tank, possibly the shaft and all. Have not decided if I want to go with a fixed blade or folding prop. I thought the bed might have to be raised about, 2-4 inches based on the drawings.
I went with the 16 because I am in Puget Sound and would like to have a little more punch when fighting 2-3 knots of current.

bvermeer 11-09-2011 11:54 PM

Beta Replacement
Hey Guys!

I'm in the process of replacing the old Volvo MD7A with a new Beta 20 sail drive unit with Gori folding prop. With a 14 x 8 prop (standard for the unit) I am told that I will be attaining 6 knots at 3,000 rpm. Max cruise for the Beta 20 is 3,600 rpm. So far the old engine is out, now time to clean and glass. I'm also stripping the bottom to repair blisters. It's going to be a busy winter!

Bert Vermeer
s/v Natasha
1978 Islander Bahama

kentg 11-10-2011 04:30 AM

Bert nice to hear you are replacing, wow a 20hp with a sail drive you are ambitious! I am half way through the project, the old motor is out, and I am fabricating the new bed rails. need to take some more measurements. I was gonna check with ya to see if you wanted parts from my old beast, but sold it on Craigs List.

Good luck to ya


bvermeer 11-10-2011 09:03 AM


I went sail-drive because I didn't want to have to deal with engine bed re-alignment. I've done a sail-drive before in a previous boat and I thought it was quite simple. Just cut a big hole in the bottom of the boat (arrrgh!!). I went with the 20 because of the three cylinders. I wanted a smoother running engine and three will be smoother than two. The sail drive system will also help smooth it out. Will you be ready for the July Islander Rendezvous at Telegraph Harbour Marina this year?

spillarc 11-10-2011 06:41 PM

Prop for Beta 16 on Islander Bahama 30
Just wanted to throw in my two cents for what it's worth.

A couple of years ago I repowered my IB30 with a Beta 16 using recommendations from the folks at Beta US. The prop is 13" x 8" three bladed model with a 50% blade area ratio from Michigan Wheel (Model DJ355). When I installed this prop it appeared much larger than the 3 bladed model I removed from the Volvo MD7A.

I believe that the prop may be slightly oversized as I have been unable to make full RPM on my Beta (3600 RPM)...Can only get to about 3100 RPM. However, at this RPM I am making hull speed. This also may be due to the throttle cable needing adjusting and I plan to investigate this further.

johnyjackson 11-11-2011 02:44 PM

I did repitch to a 9, not 8, and I had the other dimention wrong, it may be 12 X 9 I'm really not certain. In any case, the 9 works much better then the previous pitch (12). With the Beta 14 (13.5 HP) I can get to max rpm, and in smooth water be very close to, or at hull speed. Also much more punch in waves or counter current. I have not checked fuel consumption yet.

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