Search found 24 matches

by Yellowjacket
Sun Sep 08, 2019 4:26 pm
Forum: REPAIRS and MODIFICATIONS
Topic: 1967 SPORT 13: Where to install gauges
Replies: 11
Views: 3994

Re: 1967 SPORT 13: Where to install gauges

Here's a couple of pic's of what I did for my 13... I used a block of Sapele and cut it at an angle and mounted an Airguide speedo and Tach on it...
by Yellowjacket
Sun May 19, 2019 12:23 pm
Forum: PERFORMANCE
Topic: Engine for classic 13-footer
Replies: 13
Views: 6967

Re: Engine for classic 13-footer

If you're really bothered about going too fast you can just adjust the throttle cable on the 35 so that it doesn't open all the way. What you can do is just select a prop that does 30 mph at the max rated rpm. That's a fine top speed for a 13 foot Whaler. Then, to prevent the motor from over revving...
by Yellowjacket
Fri May 17, 2019 9:22 pm
Forum: PERFORMANCE
Topic: Engine for classic 13-footer
Replies: 13
Views: 6967

Re: Engine for classic 13-footer

When I was a kid we had a 13-footer with a Johnson 40--the maximum power--but the boat wasn't all that fast. It did about 34-MPH. We'd lock the throttle wide-open and the boat was very stable. The boat didn't do anything silly even with a bunch of 15-year-old kids in it. It might have gone faster wi...
by Yellowjacket
Fri Jan 25, 2019 10:20 pm
Forum: PERFORMANCE
Topic: Power-weight-speed scaling law
Replies: 12
Views: 4797

Re: Power-weight-speed scaling law

Crouch's approach works fine for a limited speed range and for hulls that are not operating at high speeds. It assumes a prismatic hull and no significant changes in setup. Since it does not consider aerodynamic lift or drag it's not going to accurately predict behavior where those aspects become a ...
by Yellowjacket
Thu Dec 06, 2018 7:05 pm
Forum: REPAIRS and MODIFICATIONS
Topic: Rage Jet Drive Cooling Modification
Replies: 5
Views: 2044

Re: Rage Jet Drive Cooling Modification

Waterjets make a ton of pressure, at high power it's over 50 psi in the area where this is tapped into. The worst case is actually at idle, where there isn't a lot of pressure, but there should be enough to pump water up to a level above the head, and so long as the thermostat is open and it isn't c...
by Yellowjacket
Tue Dec 04, 2018 7:49 pm
Forum: PERFORMANCE
Topic: SPORT 13 with 9.9-HP
Replies: 17
Views: 6291

Re: SPORT 13 with 9.9-HP

When I was a kid in Florida if your motor was less than 10 hp you didn't have to register the boat. That is one reason that Mercury "Super 10's" were really popular, they made about 16 hp. The old "green tank" Merc's are still around, but the ignition is pretty archaic and they a...
by Yellowjacket
Wed Nov 21, 2018 5:53 pm
Forum: PERFORMANCE
Topic: 13 GLS and Large Stern Wave
Replies: 12
Views: 5525

Re: 13 GLS and Large Stern Wave

Get some weight forward. The more weight you move forward, the lower the wake will be. If it's a 13' boat, jut putting one person on the bow seat will significantly reduce the wake. With too much weight aft, you are pushing a lot of water and the wake will be much bigger.
by Yellowjacket
Tue Sep 25, 2018 8:49 pm
Forum: REPAIRS and MODIFICATIONS
Topic: Water Pressure Gauge
Replies: 7
Views: 2041

Re: Water Pressure Gauge

Typical pressure gages are just Bourdian tube gages and they can indeed go bad. The needle is connected to a bent tube that changes shape when pressurized. There is a linkage and a gear in there that spins the needle as the tube changes shape. If the linkage or gear breaks then the gage won't work. ...
by Yellowjacket
Wed Sep 19, 2018 10:50 pm
Forum: PERFORMANCE
Topic: Classic Whaler 13 Hull Modifications
Replies: 6
Views: 5732

Re: Classic Whaler 13 Hull Modifications

I spent an hour or so on my back under the transom on a creeper doing some preliminary measurements and figuring out what the mod is likely look like. What I will do is run a Savitsky spreadsheet that can predict performance for various planing surface widths and come up with a width that will get u...
by Yellowjacket
Tue Aug 28, 2018 9:26 pm
Forum: REPAIRS and MODIFICATIONS
Topic: Mercury 90-HP: Shearing Flywheel Key
Replies: 5
Views: 1704

Re: Mercury 90-HP: Shearing Flywheel Key

Keyed flywheels use a tapered crank. Any time you shear a key you need to carefully inspect the shaft and flywheel and if there is no damage to the crank or flywheel, the key can be replaced and the timing will be fine. Tapered cranks fit tightly and, when properly torqued, the taper is what transfe...
by Yellowjacket
Sat Aug 25, 2018 8:42 pm
Forum: PERFORMANCE
Topic: 1984 Sport 15; E-TEC 60 H.O. Mount Height
Replies: 37
Views: 11216

Re: 1984 Sport 15; E-TEC 60 H.O. Mount Height

The old Merc 500's 50-HP was a flywheel rating, that is, it was the power rating for the powerhead, without the lower unit. Outboard engine power ratings changed in the mid-1980's to be measured based on propeller shaft horsepower. When the rating system changed, the same Merc 500 engine was rated a...
by Yellowjacket
Mon Aug 13, 2018 9:00 pm
Forum: REPAIRS and MODIFICATIONS
Topic: Pitot-tube Speedometer Diagnostic Methods
Replies: 1
Views: 936

Re: Speedometer not working

No, you need pressure to check the gage, and the amount isn't that small. That is, you probably can't blow on the tube enough to make it register. Here's a typical calibration for Teleflex speedometer: 5 PSI = 20 MPH 11 PSI = 30 MPH 19 PSI = 40 MPH 30 PSI = 50 MPH If you have a pressure gage or hook...
by Yellowjacket
Fri Aug 10, 2018 10:44 pm
Forum: REPAIRS and MODIFICATIONS
Topic: 1978 Mercury 50-HP Oil Leaks from Gear Case
Replies: 4
Views: 1541

Re: 1978 Mercury 50-HP Oil Leaks from Gear Case

Best thing to do is to clean the paint and bondo off and see what the problem really is. Seals generally leak and that's the usual reason for leakage. Just because someone used bondo on the lower skeg area doesn't mean the case was cracked. You've got to really hit something hard to crack a case. Fi...
by Yellowjacket
Fri Aug 10, 2018 9:24 pm
Forum: PERFORMANCE
Topic: Yamaha’s “logical boat speed” formula
Replies: 5
Views: 4375

Re: Yamaha’s “logical boat speed” formula

What the Yamaha site is calling "efficiency" is really just slip. Mercury is calling it slip, which is what it is. Yamaha is calling it "efficiency", but it really isn't efficiency. The folks at Yamaha may want to "dumb it down" for public consumption but what they are ...
by Yellowjacket
Wed Aug 08, 2018 10:01 pm
Forum: PERFORMANCE
Topic: Classic Whaler 13 Hull Modifications
Replies: 6
Views: 5732

Re: Classic Whaler 13 Hull Modifications

I've been running my 13-footer with [a late 1970's Mercury 50-HP two-stroke-power-cycle four-cylinder outboard engine]. This engine isn't all that light, but it's a lot lighter than most modern motors. I don't have power tilt or trim, so that takes a bit out of the equation. I've run a couple of dif...
by Yellowjacket
Sun Oct 15, 2017 9:27 pm
Forum: PERFORMANCE
Topic: Classic Whaler 13 Hull Modifications
Replies: 6
Views: 5732

Re: Classic Whaler 13 Hull Modifications

Your investigation into modifications to the running surface of the classic Boston Whaler 13-foot hull is bound to be interesting. I look forward to hear more from you about your experiments and from others who can contribute to this discussion. Thanks, I have a Savitsky analysis spreadsheet that c...
by Yellowjacket
Wed Oct 04, 2017 11:20 pm
Forum: REPAIRS and MODIFICATIONS
Topic: Trailer Spindle
Replies: 8
Views: 3803

Re: Trailer Spindle

You might as well just go get the sleeve, that pitted surface will chew up a seal if you tried to run a seal on it. If you can move the seal in or out relative to where the pitted area is you can get it to work. One way to do that is to put a couple of washers, so that the total thickness of the sta...
by Yellowjacket
Wed Oct 04, 2017 11:09 pm
Forum: PERFORMANCE
Topic: Classic Whaler 13 Hull Modifications
Replies: 6
Views: 5732

Classic Whaler 13 Hull Modifications

I was thinking that it might be beneficial to create a hull modification thread for the 13 foot original Whalers. While the 13 footer was developed in 57 and went into production in 58, a lot has changed since then in terms of planing hull technology and of course motors have come a long way too. Wh...
by Yellowjacket
Mon Oct 02, 2017 7:33 pm
Forum: REPAIRS and MODIFICATIONS
Topic: Trailer Spindle
Replies: 8
Views: 3803

Re: Trailer Spindle

Look up "speedy sleeves" and if the seal areas are badly pitted you can put them on and not have to replace your axle. They work and are made of stainless steel so you shouldn't have a problem with corrosion when they are properly installed. A new set of seals and sleeves should do the tri...
by Yellowjacket
Mon Oct 02, 2017 7:24 pm
Forum: REPAIRS and MODIFICATIONS
Topic: 1978 Mercury Leak Near Propeller
Replies: 7
Views: 2507

Re: 1978 Mercury Leak Near Propeller

It could be the lower unit rear seal, but most likely it is "spooge", a mixture of oil and unburned fuel. The lower unit lube can easily be checked, pull the plug and drain the oil and check for water in the oil. If it isn't contaminated, refill with fresh oil. You should drain and check t...
by Yellowjacket
Sun Oct 01, 2017 2:22 pm
Forum: PERFORMANCE
Topic: Using Crouch's Formula to Predict Waterlogged Hull
Replies: 6
Views: 2772

Re: Using Crouch's Formula to Predict Waterlogged Hull

There are too many variables in setup that can creep into the equation. Prop pitch, trim angle, weight distribution and too many other variables would distort the effect of the overall weight. Unless you're carrying a few hundred pounds more is isn't going to show up. If you've lost speed and know t...
by Yellowjacket
Sun Oct 01, 2017 2:06 pm
Forum: REPAIRS and MODIFICATIONS
Topic: Sapele and Mahogany Lumber Source, Uses
Replies: 9
Views: 4268

Re: Sapele and Mahogany Lumber Source, Uses

Keim Lumber in Charm Ohio I bought sufficient sapele for my 13' and the wood delivered was excellent 5/4 planed and sanded on one side. Total spent was around $200 plust shipping and that included wood for the front hatch as well as a backrest and backrest brackets. I used 5/4 for the console seats ...
by Yellowjacket
Mon Jul 31, 2017 7:00 pm
Forum: REPAIRS and MODIFICATIONS
Topic: Anchoring Steering Transom Pulleys
Replies: 4
Views: 1564

Re: Anchoring Steering Transom Pulleys

Thanks, I see photos of earlier 13 footers that don't seem to have any thru bolts, so maybe it was earlier boats that just had screws in them...
by Yellowjacket
Mon Jul 31, 2017 9:42 am
Forum: REPAIRS and MODIFICATIONS
Topic: Anchoring Steering Transom Pulleys
Replies: 4
Views: 1564

Anchoring Steering Transom Pulleys

I'm putting steering pulleys in an old Whaler and was looking at how they pulleys at the transom were anchored. My pulleys have the typical "U" shaped stainless mounts with holes for 2 #10 screws in them. Most photos I can find show these mounted on the transom or in the corner of the tran...