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ContinuousWave: Whaler Performance
Mounting of setback bracket on Montauk
|Author||Topic: Mounting of setback bracket on Montauk|
posted 06-09-2001 06:52 PM ET (US)
I just received my Springfield marine 6-inch set-back bracket, and plan on rigging it this weekend. Before I start I was wondering if there are any special precautions or tips I should consider and follow before I get started? I patched and filled all previous holes and had a friend of mine re-gelcoat the entire transom. Any advice would be much appreciated. Thanks, Marc
posted 06-10-2001 10:35 AM ET (US)
I'm sure we'll all be waiting to hear what this does for your hull performance. Keep us "posted." BTW,, why did you have to have the transom re-gelled and holes filled? Does the bracket have to have different holes?
posted 06-10-2001 10:58 AM ET (US)
I put a CMC two piece manual bracket on my Montauk and I was able to use the upper two holes but unfortunately had to make two new lower holes. All has worked out well though.
Mine allows for about 5 inches of vertical adjustment and has 5.5 inches of setback. To adjust the height I loosen 2 1 1/8" bolts on each side then use a socket to turn the adjustment bold. It really is a simple operation but wouldn't do it while the boat is in the water.
I think I found the "sweetspot" for the engine height. The cavitation plate of the 115 Ficht is about 1.5 inches above the hull bottom. This allows for great performance but still doesn't suck air.
I sent in a photo of this so hopefully it will be posted here soon. Rex
posted 06-10-2001 11:15 AM ET (US)
My Springfield Marine bracket (10" set-back) mounted in the existing 200 Yamaha outboard holes. I rented a hydraulic engine hoist from U-Haul ($19.95/day) and it was a fairly straightforward switch. The Yamaha comes with a lifting ring so I did not have to buy one. I did buy all new SS bolts and nylock nuts for both the bracket-to-transon and engine-to-bracket mounting. All my cables and lines were long enough for the 10" set-back so this was one of my easier projects. Good luck.
posted 06-10-2001 11:32 AM ET (US)
Just a follow up. Since yours is going to be basically a "new" installation, make sure the bracket is centered on the transom. I can't help but think you're going to be redrilling your old mounting holes, at least the top two. Caulk well around the perimeter of the bracket and holes.
posted 06-10-2001 04:56 PM ET (US)
Standby for some pictures of Bracket mounted engines on Montauk, from Rex and others, coming up soon in CETACEA.
posted 06-12-2001 09:04 PM ET (US)
can you tell me how your boat performance after installed jackplate, and how shallow she can run on plane? becuase i will put one on mine, with it can ran more shallow than before, thanks
posted 06-12-2001 09:35 PM ET (US)
Sorry but I don't know just how shallow she will run in, I haven't been that daring yet. I typically run with the engine about 1.5 to 2 inches above the hull bottom. So I know I can go in a little bit more skinny water than before but no major shallows. The Montauk is not really a flats, shallows boat but I think more of an all around bay boat.
By raising the engine I see that I have gained about 200rpm so remember you may have to change to a different prop if you were already pushing max rpm's.
I rigged the boat with the jackplate and never ran it before that so I can't tell you how is was before and after installation. Rex
posted 06-12-2001 09:40 PM ET (US)
Just to clarify: I typically run with the -cavitation plate- about 2 inches above the hull bottom when I know I will be in the shallow areas. Rex
posted 06-13-2001 07:19 PM ET (US)
Because of this site, the discussions on setback plates and Jim's super reference article on engine brackets, I decided to add a jackplate to my 74 Montauk with '89 90hp Merc.
The jackplate is an 8" Rite-Hite that I purchased of off eBay. I paid $202.50 for a unit that retails for $375. I had previously lost an auction there on a 10" Springfield unit.
The install turned out to be a little more work than I thought it would be. I had to drill new holes in the jackplate to get it to match the existing holes in the Montauk's transom. While the distance between the holes was the same, the height between the holes on the transom was 7-1/4" while those on the jackplate were 8" (I believe that is standard). Because of the where I put the new holes on the jackplate I had to use shorter mounting bolts for the lower pair. I also added a transom support plate, "new" lower pitch (19") Stiletto prop, Doel-Fin, and a longer fuel line. I also sent Jim some pics.
I've had the boat out twice now. The first time I didn't notice that much difference. RPMs were good but the top speed was about where it was last fall. I had expected some speed improvement due to the prop and the jackplate. The engine was set just a little higher than it was previously without the jackplate. The cavitation plate used to be about 1 to 1-1/2" above the bottom of the boat. I would guess that while raising the engine may have increased the RPMs, the higher pitch prop (old was 17") reduced them. Also I think the Doel-Fin was producing some drag. Speed was about 38 mph as shown on the Hummingbird sounder.
I raised the engine another inch (cav plate about 3" up now) and looks like I gained another mph. Wish I had a GPS to more accurately check the speed. I think I could still raise it another inch.
Handling with the Doel-Fin did seem somewhat improved with easier steering, better stability, and lower planing speed. If I had that GPS I would be tempted to try some runs with the Doel-Fin on then off to compare.
posted 06-13-2001 07:47 PM ET (US)
Barry - I would think that you should not have the engine up over 2" with your setup. Too high, and you can lose speed, and also suck air into your cooling system with disasterous results. I would also think that a strong Merc 90 should run close to 48/50 on a normally equipped Montauk, especially since yours is the lighter, earlier 16' hull. You probably have engine problems you're unaware of, killing your HP. According to Merc's prop charts you should be running 20 or 21" prop on that engine. I'd have the engine professionally checked out, including compression.
As far as the Doel Fin is concerned, if you're really running the anti-cavitation plate 2" above water, it will have no effect on top speed, but it's drag may hurt acceleration until planing is reached and it clears the water. It works like a little trim tab. running in air, out the water, it should have no effect on steering. It's increased engine height that reduces steering torque.
posted 04-20-2007 03:40 PM ET (US)
[About six years later...] Something is not right with your motor. I am running two Whaler's: 1977 Newport 120 Johnson Big Block 13-1/4 X 17 58-MPH no jack plate set 1-inch above keel line, and 1966 Nausett 1985 Johnson 85 42-MPH with no jack plate set at keel. With a fairly new motor you should be running well into the 40-MPH range.
posted 04-21-2007 08:15 AM ET (US)
Check the date of the post, you are replying to a six year old post, either the problem with the engine blew it up or, he sold the boat. Jack
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