Sport E vs Sport G

[WaterZebra]

Did these classes ever run together? Were the Sport E (OMC 3 cyl) racers just as fast as the Sport G (Merc 4 cyl) racers? Did any of the Sport E guys ever "step up" to run Sport G?

[lars strom]

Well..in the UIM Offshore 3 / E class was always faster than the H class using Merc 4 cyl 80/85 HP.

Yes..thats me in the E-99 Piraya/Evinrude 65 HP passing the H-24 Joker/Merc cyl 80/85 HP.
The year is 1973.
A Merc 650 3 cyl on the same boat (Joker #24) was also faster than the heavier and pretty slow Merc cyl 80/85 HP.

https://www.screamandfly.com/attachment.php?attachmentid=489577&d=1507570026

[lars strom]

This is from Roslagloppet Offshore Race 1975..by far the largest Offshore race in Scandinavia.

The E class winner was Lars Ström/Christer Helin Piraya/Evinrude 75HP.
Average speed over around 125 miles was 49,8 Knots
1.7 Knots faster than the:
H class winner Jukka Huutanen/Matti Valkoinen Argo/Merc 4 cyl 80/85 HP 48.1 Knots

https://www.screamandfly.com/attachment.php?attachmentid=489583&d=1624840658

https://www.screamandfly.com/attachment.php?attachmentid=489584&d=1624840666
https://www.screamandfly.com/attachment.php?attachmentid=489598&d=1624891794

H-class Argo/Merc 80/85 4cyl.

[WaterZebra]

This is from Roslagloppet Offshore Race 1975..by far the largest Offshore race in Scandinavia.

The E class winner was Lars Ström/Christer Helin Piraya/Evinrude 75HP.
Average speed over around 125 miles was 49,8 Knots
1.7 Knots faster than the:
H class winner Jukka Huutanen/Matti Valkoinen Argo/Merc 4 cyl 80/85 HP 48.1 Knots

https://www.screamandfly.com/attachment.php?attachmentid=489583&d=1624840658

https://www.screamandfly.com/attachment.php?attachmentid=489584&d=1624840666
https://www.screamandfly.com/attachment.php?attachmentid=489598&d=1624891794

H-class Argo/Merc 80/85 4cyl.

I noticed that the OMC SE engines have bungees arounnd their mid sections. Was the power trim OEM stock?

[lars strom]

I noticed that the OMC SE engines have bungees arounnd their mid sections. Was the power trim OEM stock?

Well..Yes, for my E-class Piraya 17 I deleted the powertrim/pump to save weight and used a trim tank instead.
(My own design in the yellow circle, close to 50 years ago)
Of course you needed a powertrim for the SE class Clerici cat.

https://www.screamandfly.com/attachment.php?attachmentid=490231&d=1626142655

[2us70]

Lars. Great minds think alike. I had exactly the same setup on my SE marathon boat.

[lars strom]

2us70

Well..Thanks..its way harder to make a boat in a smaller class to go fast..and weight is a big part of that.

[2us70]

I sealed off a couple of feet of the hull and deck at the bow to be the tank. Having the water weight at the very bow allowed trim effect using less water weight. The ballast tank also let me plane off with a 3 hour fuel load in the boat.

[WaterZebra]

Well..Yes, for my E-class Piraya 17 I deleted the powertrim/pump to save weight and used a trim tank instead.
(My own design in the yellow circle, close to 50 years ago)
Of course you needed a powertrim for the SE class Clerici cat.

https://www.screamandfly.com/attachment.php?attachmentid=490231&d=1626142655

Weren't trim ballast tanks eventually banned from APBA / UIM? Or were the rules changed where you had to make min weight with these tanks empty? I know that S&F members are still using these set ups on their own non racing rigs and the tournament ski boat builders use "gunnel bags" for bigger low speed wakes for wakeboard jumping. Always thought that your own method of picking up water for engine cooling (pitot tube or prop blast) should have been allowed rather than relying on stock water pump inlets and impellers. The world record OMC V8 project ended up using prop blast pitot tube pick up just like the K&B gas model outboards use.

[2us70]

Every once in a while somebody would get caught using a auxiliary water pickup. This allowed running the motor higher than it could pick up enough water naturally to cool the engine. If you had the right prop you could run the motor high enough that it could not make enough water pressure to reach the top of the motor. The inline 6s had a problem with this. The inline 4s not so much.