Whaler Central - Boston Whaler Boat Information and Photos

Posted by jimmyrinaldi on 09/30/11 - 11:01 AM

OK guys... I am listening with an open mind ready to learn new stuff... : )

I have cured my stability issue with Tabs on my 1992 16SL 1992 Yammy TLR. My engine is mounted all the way down. I have 4 heights to choose from. I have what I believe to be a steel 3 blade prop with only one mark on it (17-K). I believe it is steel because it felt too heavy to be aluminum when I had it off. Before my tabs I maxed out at 40mph with a fin and almost an empty tank. The boat was a bronco... With Tabs I have complete stability but have lost 5mph... A fair trade as far as I am concerned.

Why should I now raise my engine ? Are there any other benefits ? I am afraid of undertaking another big project at this point with out being convinced it will improve hull performance...

I have posted my cav plate hull shot and my prop on my personal site... My cav plate looks even with my hull bottom. Is there room to move it up ? Anyone know what kind of prop I have ?

Edited by jimmyrinaldi on 09/30/11 - 4:26 PM

Posted by thegage on 09/30/11 - 1:42 PM

Raising my engine two holes--an inch and a half--makes it feel like a different (better) boat. A check shows my AV plate just showing at WOT trimmed out. Maybe I can go up another hole, but I have to wait until I have a better prop to try that. I'm going to take off my tabs this weekend and will report back after testing. I'll also post some pictures too.

John K.

Posted by Tom W Clark on 09/30/11 - 10:49 PM

Your prop is a 13" x 17" Yamaha's K series "Painted Stainless Steel" propeller (thought the paint is all worn off now), Yamaha part #688-45930-02-98. That is not a bad propeller.

I suggest the motor be raised as high as it can go. Your porpoising problems will (mostly) go away and you will gain back your top speed...and then some.

Upgrade to a 13-1/4" x 16" Yamaha Performance Series three blade, Yamaha part # MAR-GYT3B-V4-16 for even better grip and speed.

Posted by thegage on 10/01/11 - 6:04 AM

jimmyrinaldi wrote:
interesting... I never get water there. I get some in the port aft compartment...

I guess the ski locker pump was an option. I think if the boat sits out on a mooring/dock heavy rains will get enough water in there.

On my personal page I adde pics of raising my engine. The Bob's lifting hook is a bit pricey ($50), but since you have to remove the lower blind hole bolts you can't use the trick of loosening the lower bolts, putting wood under the skeg, and then cranking up your trailer jack.

I don't know if Bob's has a hook for the Yamaha, of if there's already something there.

John K.

Edited by thegage on 10/01/11 - 6:10 AM

Posted by jimmyrinaldi on 10/01/11 - 11:38 AM

#11

My yammy has mounting slits on the bottom too. I should be able to plug the blind holes and use through transom bolts on the bottom. That means I can jack the motor up and rebolt up top then drill the bottom holes with the motor already in position... If they are in line with the bolt slits below, I may be able to make this adjustment with out any drilling at all... That makes is sound easy doesn't it ?

Edited by jimmyrinaldi on 10/01/11 - 11:43 AM

Posted by Joe Kriz on 10/01/11 - 11:43 AM

#12

You want to make sure you drill the correct bottom holes so you can lower your engine if necessary. Or, if a different engine is mounted sometime in the future...

The other 16SL owner said he drilled the Yellow holes in this diagram.
http://www.whalercentral.com/articles...icle_id=82

Posted by Tom W Clark on 10/01/11 - 3:01 PM

#14

I can see in the twelfth photo on your Personal Page that the Yamaha is mounted without any bolts showing in the lower slot. This means the blind holes have been used and you will have to fill those holes and drill two new ones to raise the motor.

Once that is done, you can use any motor now, or in the future, without any more drilling because all outboard manufactures use the same bolt pattern.

Yes, mounting the motor too low is a very common problem. Your motor should never have been mounted that low in the first place.

The trouble is that 30 or 40 years ago, there just were no propellers that could tolerate the higher motor mounting positions so the motors were set down on the transom. Dealers got used to doing it that way and even to this day, many long time dealers and outboard mechanics insist the motor needs to be set low. It doesn't

Posted by thegage on 10/01/11 - 3:57 PM

#15

jimmyrinaldi wrote:
I saw that. The more I look at it the more I think I may not have to drill holes at all.

No, you will have to drill holes. I know because I just did it. The holes that the blind bolts are in do not line up with the slots. As noted in the link Joe gave, the yellow holes are the best as they will allow the washers to clear the bottom of the recess, and also allow the engine to be mounted one hole up; they will not allow the engine to be mounted all the way down. Feel free to keep PM'ing me for advice.

John K.

Posted by thegage on 10/01/11 - 4:23 PM

#17

Yes. Look again at the article. It shows you where you need to measure and drill. In the tenth picture down on my personal page you can see me starting the process of measuring and drawing lines for where to drill. The lower drilled holes in that picture are the blind holes. You can clearly see that the slots line up inside the blind holes.

John K.