Thanks Thanks:  0
Likes Likes:  0
Results 1 to 8 of 8

Thread: UIM F-4S Class

  1. #1
    Team Member Smokin' Joe's Avatar
    Join Date
    Mar 2007
    Location
    Texas and Tirol
    Posts
    657
    Post Thanks / Like

    Default UIM F-4S Class

    This is a class with tunnel size comparable to SST 60 but with a severely rev-limited 4 stroke 60 c.i. 60 hp Tohatsu (Mercury). The motor is geared at about .545, comparable to the SE/SST60 OMC gearing of about .535. The prop of choice is advertised as the Mercury 12x22. However, the winning props so far seem to be 11-11 1/4x22 Mercury props. Hubs are required, the Mercury prop 12x22 is a hub-prop. Top speeds on the course are reported to be about 108-110 km/h, or 67.5-68 3/4 mph. This sounds reasonable, as the 1985 SD kilo record (Hauptner/Evinrude 60) was 69.9 mph. The problem with the lumbering 4-strokes is weight (top heavy) and acceleration. Note that running 11-11 1.4" dia. with that gear ratio seems pretty strange, both SE and SD (as well as SST 60) ran at least 12 1/2" dia. with a hub.

    Uwe Brettschneider, who's active in the class, asked me for prop help (contact made via Holger Arens of Arens Motoren, Berlin). We therefore stopped for a Mon. afternoon at the ADAC Sportbootzentrum (Alt Gatow 1-3) on the Havel in SW Berlin, where testing is allowed on the river M-F 15-18:00. Uwe had about a dozen props, all of too small diameter to be any good. I'd refused to work on the small dia. props so he tested one that he'd sent to 'Rolla' (apologies to Phil Rolla, who's no longer there) in Switzerland. As I expected, it did not perform. Uwe somehow had three hubbed Dewalds, all had originally been 12: dia., but someone had whittled them down. None had any cup, all cup had unfortunately been ground out! One had about 11 3/4" dia. so I cupped the tips best I could and reworked the leading edge. I knew that this would at least shoot him off the bank and out of the turns, and would not hurt the top speed. However. When he hit the throttle the prop ventilated healthily (as it must for good acceleration), the motor hit 6200 RPM immediately and the rev limiter sent the RPM back to 4000, a dog of a result.
    I'm in Austria, have the prop and am taking it back to Houston for measurement. I'm quite sure that the right answer is a 12 1/2" dia. SST 60 prop. As always, the problem is for the driver to find a sponsor with deep enough pockets to fork out over $1000 for a single prop. Uwe's wife, Dani, is his pit chief and she's good at it. They're nice people.
    The tunnel is by Mølgård/Mølgaard.

    I gave Uwe and his main sponsor some advice about squaring the trailing edges, removing the external water pickup and unplugging the intake above the gearcase hub. Then we headed south back to Austria, where we have 6 old OMCs in our landlocked cellar workshop, some rebuilt, the rest to rebuild. The prop shown on the back of my t-shirt is Tracy Hawkins' 9x16 Rolla, too small a dia. for F1Sport but otherwise very good.

    Let me take this opportunity to complain about BRP. BRP is not OMC. They don't advertise, they don't promote, they sit in Canada and pay no attention to the fact that their motors are barely sold in the U.S. and are not sold hardly at all in Europe. F-4S is restricted to 60 c.i. 4-strokes 'because they are clean'. The Evinrude E-Tec has 60 c.i., 60 hp, is cleaner than the 4-strokes and would blow the Tohatsu away on acceleration. It also (unfortunately) has a rev limiter and, unfortunately for racing, is geared less that 2:1, as were the old OMC SD motors. Why isn't Evinrude in the class? Pure politics. The dealers for 4-stroke motors propagandize all over Germany that 2-stroke motors will soon be outlawed, which is pure crap. The E-Tec meets the EU environmental restrictions and is even allowed on 'pristine' Bodensee. Tohatsu is there, and Evinrude is not, because Mercury went to the trouble to get their class approved by UIM and ADAC. BRP, stated simply, seems not to give a damn whether they sell Evinrude outboards or not. They sit back and take no action, nothing seems to matter to the Canadian company.
    Attached Images Attached Images      

  2. #2
    Team Member
    Join Date
    Feb 2005
    Posts
    271
    Post Thanks / Like

    Default uim F-4 class

    I did not know the engine was a Tohatsu & i didnt know they let them rework the LU.So you think geting rid of the water pick up is better? Would you get rid of the nose cone also? Nice tread keep us informed.

  3. #3
    Team Member Smokin' Joe's Avatar
    Join Date
    Mar 2007
    Location
    Texas and Tirol
    Posts
    657
    Post Thanks / Like

    Default

    Quote Originally Posted by dave hensel View Post
    I did not know the engine was a Tohatsu & i didnt know they let them rework the LU.So you think geting rid of the water pick up is better? Would you get rid of the nose cone also? Nice tread keep us informed.
    Darrell Beaulier, who watched the class run and collide in several races in the Middle East and Europe told me it's a Tohatsu. Nose cone looks strange but keep it. Looks like 2 nose cones. Why two? I would estimate that the external waterpickup costs 1-2 mph from previous experience. Get a water pressure gauge before you remove the pickup and unplug the holes. OMC made the gauges, can buy them from Seaway Marine in Seattle http://www.marinewholesale.com/pages/OemParts.Both SST 60 and the old SE class ran with 'dry' bullet and had no problem getting enough water from the sponson edges.

    Our prop and classic outboard restoration website is mccauleyandson.com.

  4. #4
    Team Member
    Join Date
    Feb 2005
    Posts
    271
    Post Thanks / Like

    Default UIM f-4 class

    joe what we do in sst 60 is jack the motor until it does not get water then you play with props. the motor would run higher & faster but would not pump water, I know I learned that the hard way cooked the power head. Testing will tell you my be spot on. Do you know where the balance point or CG of these boats are?

  5. #5
    Team Member Smokin' Joe's Avatar
    Join Date
    Mar 2007
    Location
    Texas and Tirol
    Posts
    657
    Post Thanks / Like

    Default

    Quote Originally Posted by dave hensel View Post
    joe what we do in sst 60 is jack the motor until it does not get water then you play with props. the motor would run higher & faster but would not pump water, I know I learned that the hard way cooked the power head. Testing will tell you my be spot on. Do you know where the balance point or CG of these boats are?
    Dave, Roddy used a pressure gauge. I built the prop that he ran at Kankakee last Sept. Don't know the bal. of the Møllgård tunnels but the Tohatsu/Mercury is heavy, Uwe had to move battery and tank forward. I told him he needs more trim, I've seen photos of the winning boats in that class, trimmed out to the limit at the finish.

    I own the SST 60 prop mentioned above and am willing to clone it. I may rent it out at Kankakee this Sept. .... . Will also have winning props for F1 and SST45 there, along with my pitch gauges if I can find someone to transport them.

  6. #6
    Team Member
    Join Date
    Feb 2005
    Posts
    271
    Post Thanks / Like

    Default pressure gauge

    problem with the pressure gauge is it reads steam. thats how I cooked the power head, showed good pressure but there was no water. I like the overflow hose by the cockpit or heat gauge. Heat gauge is a little slow. Just my opinion. sorry to get off topic.

  7. #7
    Team Member Smokin' Joe's Avatar
    Join Date
    Mar 2007
    Location
    Texas and Tirol
    Posts
    657
    Post Thanks / Like

    Default

    Quote Originally Posted by dave hensel View Post
    problem with the pressure gauge is it reads steam. thats how I cooked the power head, showed good pressure but there was no water. I like the overflow hose by the cockpit or heat gauge. Heat gauge is a little slow. Just my opinion. sorry to get off topic.
    Dave, sounds like you were high enough for a kilo run! Steam should provide lower pressure reading due to compressibility. How about water pressure+temperature gauges then? There's also the old OMC warning horn that thremo-couples directly to the powerhead. Joe

  8. #8
    Team Member
    Join Date
    Feb 2005
    Posts
    271
    Post Thanks / Like

    Default uim e-4s class

    joe presure did drop but still had presure was on a long course & knew it would get more water at the turn but did not make it to the turn. o well driver eror! the heat horn is a good idea I was going to do just that but decided to go with the water tube. What I needed was an elec shock. ha ha.

Thread Information

Users Browsing this Thread

There are currently 1 users browsing this thread. (0 members and 1 guests)

Similar Threads

  1. Who's Who in Boat Racing
    By Mark75H in forum Boat Racing Encyclopedia
    Replies: 395
    Last Post: 09-30-2017, 08:50 PM
  2. "Name That Outboard"
    By Tomtall in forum Outboard Racing History
    Replies: 381
    Last Post: 12-01-2011, 08:40 PM
  3. Entry level class info!!!
    By T-REX in forum BRF Open Discussion
    Replies: 1
    Last Post: 08-20-2005, 03:27 PM
  4. Australian Junior Racing
    By Drats in forum BRF Open Discussion
    Replies: 5
    Last Post: 03-20-2005, 11:53 AM

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •