Pearson 35 Upgrading to 2 to 1 reduction

[jeffgerritsen]

Hey folks,
I have a P35 with the A4 and it's beginning to show it's age a little. I've given a lot of thought to re-powering with the Beta 28 but the price tag is around 9K with me doing all the work.

As I begin to run the prop calculators, I'm finding out an A4 with a 2:1 gear reduction puts out about the same HP and close to the same torque as the Beta 28. Rebuilding the A4 and adding a 2:1 gear reduction (doing the work mostly myself) is about 1/3 the cost of the Beta 28 option.

The questions I have are:
1. Will the 2:1 reduction unit fit the P35's limited engine compartment without reworking cabinets (IE needing to slide the engine forward because of the added six inches from the reduction unit), or can I use the existing A4 mounting holes and shorten the prop shaft? Note, this is why I gave up on the Universal M35B (Gallery Marine is running a special on them for $7387).
2. I have the 7/8 prop shaft and the A4 diagrams specify reduction units using 1 or 1 1/8 bore/key ways. Do I need a new shaft log, just a "thinner" cutlass bearing, or adapt the bore / key way and keep the 7/8 shaft? After all it maybe six inches shorter!
3. Finally, from all you 2:1 folks out there, is the upgrade to the 2:1 reduction gear really worth it?

Thanks,

Jeff

[High Hopes]

Wow, similar thoughts to mine. I have thought at length about the 2:1 gear box and every time I come up with the same questions as you. My conclusion along the lines of that old adage, "In for a penny, in for a pound." Changing the shaft is the kicker.

I do not know why a prop solution is not available that will let the A4 rev at 2700 or so. Maybe all prop makers just think diesels (1800 rpm) and can't get out of that box. But for whatever reason, we are stuck with operating the A4 at lower speeds.

If I ever re-power, I will go electric. The cost is about $3000 for the kit and $1000 for a battery. The gearing can be easily changed to accommodate any prop pitch. I could sell my A4 for $5000? That leaves another $1000 for an emergency portable generator. That would also keep the mistress cool with the AC.

Here is a link.

http://www.boatdesign.net/Directory/Propulsion/Electric/

Good luck with your decision Jeff.

Steve

ps You will probably want to leave your existing shaft alone. The change in diameter would be done where the engine drive shaft flange and the prop shaft flange meet. Probably some custom machining, but I haven't explored that part much.

[ArtJ]

The Indigo propeller on a straight drive A4 will allow 2400 rpm max.
Maybe you could get by with that. Also, maybe speaking to Tom
Stevens of Indigo, he may be able to offer additional suggestions.

Regards Art

[ArtJ]

I have a straight drive A 4 in my Tartan 34C which is 34.5 feet and 11500
lbs. The Indigo prop allows for 6.6 knots in calm seas and a good 5 knots
or better in fairly tough seas.

[hanleyclifford]

Jeff - Your interest in the 2:1 is right on target for those of us with bigger/heavier hulls. I did the change over to reduction on my boat and it has made a world of difference. I can now plow my way thru tides just about anywhere I go. Best modification I ever made on Destiny and I have made a few (see my albums). It is easy to switch cutless bearings; step up to 1". Since you will have to get shaft work done anyway this is a good time to just get a new one. The marginal cost will be small. Raising the engine about 1" is easy. Just make sure you have the extra room aft to extend the engine assembly. If you do proceed I can supply exact measurements and photos to help. Just do it. Regards, Hanley

[jeffgerritsen]

Thanks folks,
For the Replies. I need to add some additional information to make the picture clearer.

First, I changed the existing prop to 11 x 5 RH. This allowed the A4 to reach 2450 rpm. There are prop solutions to allow the A4 to reach 2700 rpm, however props become very inefficient at those speeds. I also looked into electric motors however I would need at least a 10 kw motor. Can't load enough batteries in the boat to provide a decent reserve.

Second, the Pearson 35 is 13,500 and including 90 gal of water, our scuba gear the, and other items the boat displaces at least 15,000 or more.

Based upon weight, I would need the Universal M35B, but its simply too big for the P35 engine compartment - if I want access to the stuffing box!

Hanley, I would be very interested in your experience installing the 2:1 reduction gearbox, especially pictures.

Finally any folks out there who own P35's who have done this upgrade? How well did it fit?

Thanks,

Jeff

[hanleyclifford]

Jeff - In putting on the 11x5 you did the only viable move available to you. You brought the rpms to where the engine wanted to be; and it is now happy. The down side is that you don't have enough prop to move the boat in conditions you are likely to encounter. In light of the additional details you provided I'm surprised your boat wasn't equipped with 2:1 on delivery. I will take a picture of my installation and post it on this thread shortly. Could you post a picture of your present set up? Regards, Hanley

[jeffgerritsen]

Posting a Picture...

Hanley,
The P35 is located in Anacortes WA, I'm in Portland OR. It will be about a three to four weeks before I travel back up to Anacortes. I'll be sure to get pictures then and post them here.

BTW, I scoured the pearson35.com website and the related discussion board site (http://hhickman.proboards.com) and found a person who had the 2:1 reduction unit installed on his P35, however in 2005 he re-powered with the Beta 28.

Jeff

[dvd]

Jeff,

I have a cal 3-30- with a 2 to 1 and my 30 footer is of course a much smaller boat. I think the only difference will be that the shaft will need to be cut down as the 2 to 1 may take up more room. Mine doesn't really look much different than the direct but i have never really paid that much attention.

dvd

[jeffgerritsen]

update on reduction gear install...

Greetings folks,
Well I found a used reduction gear. It came with the reversing gear and aft housing (early model). Also picked up a used starter for a spare.

I've been re-evaluating the situation. I not going to overhaul the engine unless the compression is low enough to warrant that step. Why spend the money unless I need to.

I'll think my next steps will be:

1. check compression to determine need for engine rebuild.
2. I'll remove engine from boat bring back to Portland.
3. I'm assuming a rebuild will not be needed - hopefully!
4. Remove head, clean out cooling passages, clean, prime, and paint.
5. Install thermostat conversion kit.
6. Remove block water jacket plate and clean out cooling passages. Note engine was ordered new with fresh water cooling so inside should be pretty clean.
7. Install cooling system bypass.
8. Install MMI flange pump.
9. Install improved oil passage-way modified accessory drive.
10. Check valves. Install upgraded valve springs.
11. Clean out oil pump screen. Oil pressure is good so (maybe) I'll skip the new oil pump gears (any input on this step fella's).
12. Install the improved brace pin.
13. Install a 1/2 inch pulley for the 75 amp alternator (if the new balmar supports the 1/2 belt).
14. Drill and install the access port for easy change of the break band adjusting bolt.
15. Install the 2:1 reduction unit.
16. Clean, Prime, and paint the block and manifold.
17. Reinstall back in the boat.

Can you fella's think of anything else???

Of course, if I need to do rings and so forth (due to low compression), I'll be into a full rebuild.

Jeff

[ndutton]

18. Submit picture for Moyer Marine pinup of the month!

[jeffgerritsen]

Update

Well folks,
After a bout with pneumonia over the winter, I'm in the process of pulling the engine. I took compression numbers and here is what I have:

Cyl# Dry Wet
1 - 112 - 140
2 - 120 - 140
3 - 120 - 140
4 - 102 - 120

Wet reading is after squirting 1/2 oz of MMO into the spark plug hole. What do you folks think about the lower reading on number 4?

Jeff

PS Pictures will follow....

[hanleyclifford]

I am more concerned about the high numbers on the other three. Your numbers suggest a build up in the combustion chambers resulting in elevated compression. Consider taking the head off for a cleaning of head and tops pf pistons.

[roadnsky]

I am more concerned about the high numbers on the other three. Your numbers suggest a build up in the combustion chambers resulting in elevated compression. Consider taking the head off for a cleaning of head and tops pf pistons.

Hmmmm, Hanley.
You've got me wondering about my numbers.
I've got 122/120/120/118 (1-4)
They've been that way since I took my first readings two years ago.
The engine runs fine.

[hanleyclifford]

The specification is 90 - 125 psi. You're still in the bracket, Bro.