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I am mounting an engine with the standard bracket and it will require me to fill the blind holes and drill new holes like has been discussed well on this site before. After looking at all the reference here, I would like to describe my plan and get some feedback to be sure I'm right.

After filling the original blind holes, I will drill the green holes at 6.5 inches below the original top holes. I understand that I should be able to use the original top holes. The top bolts will be mounted through the last of the top holes...(see picture of the bracket on personal page. The bottom bolts will be mounted through the first of the bottom holes. If I measured right this will place the top of the bracket aboutt 1.5 inches higher than the top of the transom? Based on what i read this is desirable?

The boat is a 1982, 17 foot custom and the engine is a 40 mercury two stroke tiller with electric start and power trim. The boat is only outfitted with a wood bench seat across the back, one battery in back, 94 QT cooler in center, and 12 gallon gas tank forward. I was also wondering what prop might be good for this setup?

Thanks in advance. Joey

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What year is that 40hp Mercury?

Most newer motors have 4 or 5 bolt holes at the top and slots at the bottom (except Mercury where some have bolt holes also at the bottom instead of slots).
See this photo of a 40hp Yamaha.
http://www.whalercentral.com/images/p..._64/13.jpg

Are you sure 40hp is going to be enough for you?
http://www.whalercentral.com/articles...ticle_id=5

I have seen a pair of 40's on the back but never just one 40hp.
The boat is rated for 100hp max and 35hp min
http://www.whalercentral.com/userphot...lbum_id=14

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The mercury is a 1999 two stroke tiller. I thought it was unusual to only have 3 holes on top as well. There are no slots on the bottom...only 3 holes there too. I added another picture of the overall outboard on my personal page.

The 40 horse tiller will be sufficient for our needs.

Thanks

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Maybe some of the Mercury experts can give you more info as I am not a Merc Man.

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Wouldn't a Jack Plate solve the issue of motor height? Saves from drilling into the transom with a "guess" at best height for the specific motor (only 3 holes of movement). Also, if a repower in the future, adjust the height of the Jack Plate instead of potentially drilling holes over again at the original location. Just my $ .02.
gchuba

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Joey -- I think your plan is good.

Yes, the smaller Mercurys only have three set of holes instead of their usual five.

Verify the spacing on the holes in the motor mounting bracket before drilling the transom.

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I do not see a jack plate as a very solution to this problem.

- If the transom holes are not BIA standard then the jack plate won't fit them either and the jack plate will need to be drilled

- The jack plate will add considerable expense to the project and may add a delay waiting for it to arrive

- A jack plate will add some setback which is the last thing a tiller steered 40 HP motor on a 16'-7" hull needs.

- A jack plate may offer more vertical adjustment but again, we are talking about a 40 HP tiller steered motor and once the best height is found I do not think it going to need to be readjusted, and three sets of bolts holes ought to be more than enough to find that best height.

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Tom, I see your point. I did not think that a 2 1/2 " set back with a smaller jack plate would create leverage issues with the tiller handle. I thought the versatility of the plate wold be an advantage for long term use. I just keep reading about all these fellows at some time or other having issues with "how many holes up?" and having to remove the motor for adjustment.
gchuba

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What versatilty does one need once the motor is set?

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Tom, along the lines of drilling holes at the incorrect starting height within the motors adjustment limits (did not take into account the body weight of a person at the tiller) or a repower down the road occurs with different engine dimensions. I was also under the impression that the jack plate improves the dynamics of a boat.
gchuba

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I don't follow you. If one can't drill holes in the right spot, they probably shouldn't be trying to install a jackplate either. A jackplate won't fix stupid.

Jackplates can have dramatic influence on a boat's handling and speed in some instances on some boats. I do not think a 40 HP tiller steered motor on a 16'-7" Whaler is any sort of high-performance rig that would benefit.

Repowering in the future is one very good reason to get the transom bolt holes on the industry standard BIA lay-out now, so its done with once and for all. Trying to accommodate those old blind holes just delays the inevitable the next time a new motor is installed. That makes no sense to me.

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Tom, I did not understand that his approach was BIA standard. I was under the impression that the method "...6.5 inches down..." was random for the motor. I thought that jack plate once mounted, would bring his bolt pattern for the motor up to standard.
gchuba

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To clear up my original thoughts.

In the OP....I mention it is a standard bracket and I will drill the green holes which are 6.5 inches below the original top holes.

Because this mount only has 3 holes of adjustment and the distance between lowest top hole and the highest bottom hole is 6.5 inches there will be no adjustment with the green holes. I like the idea of drilling the green holes instead of the yellow to avoid the bottom of the splash well. Mounting this engine with the green holes will leave the bracket 1.5 inches above the transom. Of course this would also allow mounting any other standard bracket in the future . I am going with this plan. Thanks guys for the feedback.

I know there are not many choices for this engine but could you recommend a prop for this setup Tom?

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I got the blind holes filled this week and replaced two of the drain tubes on the transom. I was ready to drill the green holes however the engine looked a little high to me so I took some pictures for some feedback. The last 4 pictures on my personal page shows the engine mounted all the way up.

Picture one: the bracket is about 1.5 inches off the transom.

Picture two: a board laying across the cavitation plate with engine trimmed all the way down.

picture three: motor is trimmed up slightly

picture four: board is in same position as 3 and engine is trimmed all the way down.

My question is will this mounting position work?

Thanks.

Joey

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In your pictures, it looks fine to me. The water height rises from the back of the transom by the time it gets your motor. You really do not need the yellow holes. I would drill the green holes.

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I'm getting ready to do the same job and have read all of the related threads. I'm not sure I understand the bolt pattern of that 40 but the reason I don't want to drill the Red holes (all the way down) is you won't have room for washers inside the splash well and drilling the green holes (all the way up) doesn't leave options if it's too high. I'm planning to drill the yellow holes (middle) and mount 2 holes up. I'll let you know how it goes.

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Whalerbob,

Drilling the Green holes will mount standard bracketed motors 2 holes up.

You would not be able to lower the engine less than that but your could go up another hole.

Remember, measure and layout both the inside and outside of the transom holes before drilling anything.

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The usual way to measure ventilation plate height is to have the plate parallel to the bottom of the hull, as it seems to be in picture three.

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Yes, picture 3 shows the engine trimmed up slightly so that the angle of the ventilation plate is close to the same angle as the bottom of the boat.

How much higher can the ventilation plate be above the bottom of the keel?

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Assuming the 7-1/4" vertical spacing can be accomplished (it's going to be VERY close!), I would use that spacing. It will mount the engine at Whaler's specified height, and should work well with any propeller. This also gives you the option of going up one more hole if needed.

With only 40 HP on that hull, your top end speed is only going to be around 28 MPH. This is not the realm of elevated engine heights are performance props, nor is tiller steering.

With engine only one hole up, and at these speeds, you can use a Mercury's surprisingly good aluminum prop with good results. If you go up one more hole, you may need a more expensive SS prop to avoid ventilation/slippage.

Later and current Mercury 40-60HP engines now have the 5 hole mounting pattern restored.

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That depends on the prop you choose. I don't think (I don't know) there are too many performance props for that gearcase. Your current position is roughly where the rest of us start, regarding that hull, and then we go up from there.

Chris

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Thanks guys...I am going to drill the yellow holes as I will have just enough room. This will give this bracket two mounting options.

I am going to order a Stiletto Triad propeller with a 10.5" diameter and a 12" pitch? are there any other suggestions for propeller choice? Remember this is a 40 HP tiller on a 17' hull.

Thanks.

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I drilled the yellow holes and mounted the engine in the highest position. The yellow holes will allow me to adjust down one hole with this particular mercury bracket. The yellow holes came in just above the bottom of the splash well and I cut the square washers to match. Updated picture on my personal page.

I will lake test the setup this week after installing the new propeller.

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Looking forward to reading the results.

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Last week I installed a new stainless stiletto triad prop with a 12" pitch and was able to finally test this engine setup. To recap, this engine is 1999 40 HP two stroke that I recently purchased and converted to tiller steer to be installed on my 17 foot boat. The engine appears to be in pretty good shape, starts easy and idles very well...However the compression is 106-106-97 and sometimes I "think" I can hear the engine ticking.

The engine is mounted all the way up and the cavitation plate is almost 2 inch above the bottom of the keel as pictured in my personal page. Overall I was very pleased with this setup...The boat was quick to plane and was a joy to handle. I noticed with the engine trimmed out that it would begin to suck air in very tight quick turns but otherwise remained planted during the entire test. the last picture on my personal page shows the cavitation plate at WOT.

The maximum RPM for this engine is 5500. I was able to get a WOT 5100 RPM without trimming the motor and saw 31 MPH on the GPS. The boat cruised well at 3950 RPM and 25 MPH.

I would like to thank everyone for the help!

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http://youtu.be/s6U-5dOOmpc

http://youtu.be/fV1YZY4IFSA

Here are 2 short videos of the test. If you listen close you may hear the engine tick that has been driving me nuts...I hope I am just hearing things.

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Good looking rig and performance for a 40 on a 17 foot Whaler.

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Yes - Very nice performance and boat. It's nice to have a light carbureted 2-stroke motor.

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Could the noise be propeller rattle
I think I have a similare sound on my engine and it only appeared with the stainless prop.
http://s921.photobucket.com/user/Petr...5.mp4.html
Also read this thread,
http://www.whalercentral.com/forum/vi...rowstart=0

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Thanks for the suggestion. Prop chatter could very well be what I am hearing. I just went out and pushed in on the prop and it will push in about a quarter of an inch and spring back out. If I do this fast enough it makes a heavy knocking sound.

When I installed the prop I torqued it to 50 pounds and it just started to crush the spacer and I stopped. I am not sure if this has anything to do with it or if the prop was designed to push in on the shaft like I described but this could very well be what I am hearing.

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The spec torque for the prop nut on my nissan 50 is around 30 ft-lbs if I recall correctly. 50 sounds high but check with a service manual to see what the factory spec is for your engine.

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55 pounds for the mercury is what I found...I did not damage the spacer, just felt like if I tightened the nut any more than it would crush...I feel certain that I could not have applied 5 more pounds without damaging the spacer.

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Then it sounds like you are good in terms of the torque and spacer.

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When I installed the new Stiletto on the Honda 50 on my 13 Whaler I noticed that the hub was not set deeply enough into the prop until I torqued the nut to specs. It may be worth the price of a washer to see if 5 more pounds of torque would eliminate the problem.

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Before you add torque and risk damage, pull off the prop and push and pull the prop shaft along its axis to see if the play is within the lower unit rather than being related to the prop.

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http://youtu.be/juOSU8MineE

I think the hub may not be seated properly. The link shows a video of me pushing in on the prop. Is this normal? Again, I do not feel that I can tighten the Prop nut without damaging the spacer.

Thanks.

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Wing15601 is on the right track. Add a stainless washer between the prop and the existing spacer (install thrust washer, then prop, then additional stainless washer, then the aft spacer, and then the nut). Be sure the inner diameter of the washer is large enough to slide over the splined portion of the shaft.

I had this same problem with my solas stainless prop on my nussan outboard and this solved the problem.

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well...I took the prop off to inspect the hub and it appeared to be seated properly. When I loosened the nut I noticed that it did not take much pressure to back it off... but I expected after testing to re-torque the nut.

After inspecting the hub I installed everything and started to tighten the prop nut and the spacer collapsed. It was just barley more than hand tight and no where close to 50 pounds. I will contact precision propeller and hopefully have a solution soon.

I put a picture of the crushed spacer on my personal page.

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So it sounds like the spacer couldn't take the force of 50 ft-lbs of torque. Sounds like maybe it was defective? Good news is it looks like you found your problem.

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I agree...I was not able to apply the proper torque to the prop nut when I first installed the prop and I think this is the cause for the ticking sound. The prop spacer seems kinda Micky mouse too me...I feel like even when I get another one it will not stand up to 55 pounds of torque. I think I should try a larger tab washer between the spacer and nut. I will update when I get it fixed. Thanks again for the suggestions!

Joey

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Those are the numbers ive been awaiting for a 40hp on that hull, its not same as ny hull, but similar. Thats going to be great on gas. An a joy with all that space in there due to no center console.

Enjoy that boat.

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I got some help from Precision propeller and found out that the spacer is a two piece spacer and has different applications. On my application only one piece of the spacer is required and I installed it with both. The part of the spacer that broke is for a different engine so I was able to use the rest of the spacer and install the prop correctly with the specified torque. This information was in the instructions however it was a little confusing because the spacer came packaged in one piece and there was also another washer in the kit that is for yet another application.

All seems good now and precision propeller was very helpful. I hope this resolves the engine tick.

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I took the boat out this morning to test with the prop installed correctly and I'm glad to report that it ran great. The engine knock that I thought I was hearing before was in fact caused by the prop and is now gone. The engine ran smooth and quite.

This morning I had 2 adults (including me), a 3 year old, and a little fishing gear, the WOT rpm was 5050 and top speed was 30. With this engine mounted all the way up I am unable to trim out much as it will begin to cavitate in turns. With the engine trimmed all the way in it is very quick to plane and reaches 30 mph without any trim. Also trimmed all in there is absolutely no cavitation.

Does anybody think that there might be something gained by lowering the engine one hole and having more trim adjustment?

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I found the same behavior on my 15 with the engine raised all the way up. I lowered the engine one hole and found the performance overall was best here for my setup (great top speed, great hole shot with controlled minimal bow rise and no aeration, great handling in turns with no aeration, and good trim adjustability). Everyone is different. Try lowering the engine one hole and see how it performs. Then you can decide which position is best for your setup.

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Yea...the only way to know is to do it. I will lower it one hole and test again before sealing everything.