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Author Topic:   Bottom bolts
whaletail posted 03-14-2002 06:13 PM ET (US)   Profile for whaletail   Send Email to whaletail  
I just asked a nearby outboard shop how they deal with the lower bolts when mounting a motor on a BW. Their answer was a little surprising. Said they cut an access door to get to em. I've never seen any done like that here! So what's the best way - lagbolts? Thanks for any help.
JBCornwell posted 03-14-2002 06:55 PM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
The BEST way, Whaletail, is to use a small, fixed jackplate so that the integrity of the hull is not compromised. Performance and ride improvements are serendipity.

Red sky at night. . .
JB :)

whaletail posted 03-14-2002 07:50 PM ET (US)     Profile for whaletail  Send Email to whaletail     
Thanks JB, but I have to ask about the lower bolts on the jackplate now. How do you get to them?
JBCornwell posted 03-14-2002 11:27 PM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
You didn't mention the boat, Whaletail, but on my Montauk the four bolts that hold the plate to the transom all fit with no special problems.

It originally had a '80 OMC V4 on it. The other side of the plate then bolts to the Suzi very neatly.

Red sky at night. . .
JB :)

whaletail posted 03-15-2002 08:00 AM ET (US)     Profile for whaletail  Send Email to whaletail     
It's a Menemsha that has no holes drilled in the transom yet, so I want to be sure. So with your jackplate, you can get to all 4 bolts from the motor well? That's also something I havn't seen on this site.
JBCornwell posted 03-15-2002 08:23 AM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
Give me a couple of hours, Whaletail. I will give you a link to a photo of my plate.

Red sky at night. . .
JB :)

whaletail posted 03-15-2002 09:09 AM ET (US)     Profile for whaletail  Send Email to whaletail     
Thanks JB. - Tom
Bigshot posted 03-15-2002 09:33 AM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Guys if you lay the engine on the transom....lower bolts are not accessible. If you raise it 1/2" or so, no problem. I have never had an issue with lower bolts on any of the Whalers I have owned.

About 3 years ago I swapped a 70 Merc for a 70 Johnson on a 15'. The Merc had tha funky ssetup with the Externat tilt rams, etc so no lower bolt holes. He called and said he can't mount the engine without using lag bolts. I said"huh?". Just raise the engine a bit so you can get the bolts in the splash well and shave the washers into a half moon to fit. He siad "Gotcha" and When i went to pick her up....perfect. No reson to dig, patch, lagbolt, etc. Just raise the motor off the transom or use a jackplate.

triblet posted 03-15-2002 10:16 AM ET (US)     Profile for triblet  Send Email to triblet     
How does a boat as old as a Mnemensha (can ANY of
us spell that) not have holes in the transom?


JBCornwell posted 03-15-2002 11:54 AM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
Okay, Tom. Here (I think) is my jackplated Suzi.

Red sky at night. . .
JB :)

rb posted 03-15-2002 12:36 PM ET (US)     Profile for rb  Send Email to rb     
whaletail-I asked the same question over on the repairs and mods forum and lhg said the same thing as jb did here and I think they are right on the money with the 6" setback bracket. I have a 1970 16' hull with the two top holes drilled out and what appears to be either two knockouts or plugged holes about six inches lower and inset approx one inch still within the motorwell. I ordered a manual jackplate from cabelas that looks like can be drilled to fit my merc 50 when it comes in. I'm going with a tiller steered setup and I hope I can reach it way back there. Good luck and thanks to all for their input. rb
Kelly posted 03-15-2002 12:48 PM ET (US)     Profile for Kelly  Send Email to Kelly     
What brand bracket did you use?
Is yours manual or power lift?
Does it also have a tilt feature?
If it is power lift, do you use that feature much and under what circumstances?
Bigshot posted 03-15-2002 01:47 PM ET (US)     Profile for Bigshot  Send Email to Bigshot     
Kelly I have a vance jackplate that is manual. It has a 5' setback and 4" of lift. I probably have it 3" above transom and am going higher. Steering remaind the same, etc. I do not see the need to jack it once you find the right height unless going across flats all the time but then a 4" would be too short and something like an 8" setback would probably be needed to get the right water flow. Mind you that once you go real high you need a low water pickup etc. I am just going for max height without blowout. Right now it handles like stock and hence why I am going a bit higher. Go on E-bay and look at "jack plate" and you will find Binders marine. That is my plate. Also get the aluminum cross member to stiffen it up, he'll know what you mean. $135.
JBCornwell posted 03-15-2002 05:42 PM ET (US)     Profile for JBCornwell  Send Email to JBCornwell     
Hi, Kelly.

My plate is fixed, with a 4" setback. I don't remember where my dealer got it, but they charged me around $85 for it.

Red sky at night.. .
JB :)

Flipper posted 03-17-2002 08:37 AM ET (US)     Profile for Flipper  Send Email to Flipper     
I had the same problem when installing a new motor on my 15. There were lower holes, but they were non-standard spacing.My solution was,like JB, to get a jackplate but I drilled two lower holes, to match the hull's, on the jackplate.It is a (manual-adjust) two- piece aluminum angle plate, not cast, so I could drill with peace of mind. I would get the same type of plate, take it apart so all you have is the two pieces of angle that attach to the hull(minus the angle that attaches to the engine)and bolt them on with the top bolts( I assume you at least have two top holes??).Make sure they're straight(measure bottom of angle to the edge of the transom),then measure between the angles to get the same distance apart all the way down.Double check "straightness", then drill to your specs.
whaletail posted 03-23-2002 12:01 AM ET (US)     Profile for whaletail  Send Email to whaletail     
Just wanted to thank everyone for the inputs. I was replying back to a question, when I had a power surge that fried my modem. Word of advice - if you have your computer plugged into a surge protector, that doesn't have a phone jack surge protector, throw it away and get a good one. $170.00 lesson for me.
TightPenny posted 03-24-2002 01:40 PM ET (US)     Profile for TightPenny  Send Email to TightPenny     
Use the blind threaded holes in the back of the Engine mount. Drill the holes to match and bolt in from the splash well. This is fairly easy to do with a template.

If you do not have the template, you can make your own using a crayon and a large piece of paper and trace in the manner they use when they trace the image on an old tombstone. Mark the centers and remember you trace a mirror image.

Lay the template on the transom and drill. Cutting access doors is butchery at its worst.

Tom W Clark posted 03-25-2002 01:09 AM ET (US)     Profile for Tom W Clark  Send Email to Tom W Clark     
The 16'/17' hull has always presented this dilemma of the lower mounting bolts of many, indeed most, outboard motors that have been put on these boats.

There are many ways of dealing with this.

Historically, Boston Whaler has recommended using lag bolts. There is nothing wrong with this. The lower bolts are not subject to any withdrawal forces except during extreme reversing. They are subject to shear forces as the motor turns relative to the boat. Lag bolts will be more than strong enough for this application.

I challenge anybody to site an example of a properly lag bolted motor having a lag bolt fail in any way on one of these boats.

Now if you have an OMC motor or one of their imitators like a Yamaha, then you can sleep easy by using the blind holes that are provided in the mounting brackets of these motors for this very situation. The draw back of using the the blind holes is that you loose the vertical adjustability of the lower slots.

If you want to preserve vertical adjustability then use a jack plate or set back bracket. These aftermarket devices may allow you to keep the bolts in the splash well but they will cost you more money. There may also be performance advantages (and disadvantages) of using these devices. Think hard before doing so.

If jacking the motor up a hole or two is what you want to do anyway then do as Bigshot suggests and just do it at the get go. Im not sure every motor on every 16/17 Whaler is necessarily going to benefit form this so again, think hard before doing so.

Now the idea of cutting an access hole to get to the transom below the splashwell is not a new one. I have seen this done on Whalers. I saw one last summer at Sekiu, WA which had an oval piece of the inner hull cut out and then just reinstalled with some hardware store window screen retainers. It looked just awful! It obviously allowed water to get in there as well.

The ironic thing is that this boat had an Evinrude 70 hp motor which I know from personal experience to have the blind holes. The owner could very easily have used them and avoided the mess he created had he only had the smarts to recognize the blinds holes for what they were, or at least to have read his owners manual!

If you are determined to cut an access port to get to the transom at least install a waterproof deck plate. I think mouning a motor this way will work in the long haul. It will plenty strong enough but it seems to rather foolish in so much as its more work for a less attractive result. It would be my last choice for mounting a motor.

lhg posted 03-25-2002 03:44 AM ET (US)     Profile for lhg    
On my 1971 16' Nauset, I did not have this problem, and the transom splash well was completely stock. Perhaps OMC engines had a non-standard engine bolt hole pattern in their earlier days.

I last had a 1984 Mercury 115 installed on this boat, all the way down using the top set (of five) of bolt holes on the engine, and it used the still applicable "standard engine bolt pattern". As can be seen from the picture of this boat in the reference section, the bottom holes of this standard bolt pattern, used with all engines today, lined up with the drain hole, which also cleared the spashwell. I do remember that as I tightened down the 1/2" bolts (nut on outside of hull), the washer was deformed a little to conform with the splashwell curve. But the bottom two bolts did enter the splash well OK, and properly secured this large engine. The fit is close, but the bolts will clear.

That engine has the identical transom bracket and bolt hole pattern as my 1997 200HP EFI's.

whaletail posted 03-25-2002 08:00 AM ET (US)     Profile for whaletail  Send Email to whaletail     
And the winner is...I think it's gonna be a jack plate. I know they're more for bass boats, but I like the idea of fine tuning the height for optimum performance (even if only 2-3 mph more). By the way, a 2002 Honda 90hp is what's going on the back,
and yes Chuck, 27 years old and still in near showroom condition!
Cook seems to make the best ones - 1/2" thick instead of competitors 3/8".
I know, I know. $200.00, but it seems like a really solid way to install it.
And about lags - a BW dealer did NOT recommend, since transoms are now made of STARBOARD! (a 3 year old dealer that didn't even know about "whalerboards").
lhg posted 03-25-2002 05:40 PM ET (US)     Profile for lhg    
Whaletail - Unless you are going with hydraulic lifting, the Cook unit is not the best designed. It is very wide and awkward looking, being boxy and wider than the engine bracket. it actually was designed to conceal the hydraulics inside the unit, hence it's large size. But in the manual version it is too wide. Springfield marine (they also make a lot of pedestal seating items) also makes theirs out of 1/2" anodized aluminum, and it is a much smaller and narrower looking unit, with a heavier duty lifting rod. There are pictures of boats rigged with both units on this site. Take a look and you'll see what I mean. Do not buy a 2 piece jack. You want the one-piece unit with the center treaded lifting shaft.
whaletail posted 03-25-2002 08:03 PM ET (US)     Profile for whaletail  Send Email to whaletail     
lhg, I just checked out Springfield Marines web site, all I could find is a "Transom tuff'ner". Nothing on Jack plates. Thanks for the heads up on CMC.

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