posted 03-28-2008 05:17 PM ET (US)        

After reading all the posts of the benefits of a jack plate I decided to try it. I purchased the Bobs convertible 5 ½ inch plate with negative trim. I choose this one for several reasons. First, It was light weight. Secondly, I could adjust it if 51/2 was to far back for my set up. Lastly, I wanted more of a negative trim angle to keep the bow down in choppy water.

Here are my results so far with it set at 5 ½ inches with the negative trim and water intakes even with the “pad” or bottom of boat. Boat jumps on plane and really sticks the bow down with the engine tucked in which is nice when the waves pick up. I use this boat for diving and fishing in the ocean and the waves can pick up quickly. The boat now sits with noticeable static trim and water is now just above the scuppers. So the boat sits almost one inch lower in the water. This is less than I thought.

The numbers all with full 12 gallon fuel tank, all coast guard equipment, extra prop, miscellaneous tools and large anchor with 8 feet of chain and 100 feet of line in bow compartment. All numbers are with Garmin GPS within the last couple of weeks.

Before jack with old 22 raker the boat would do 51 mph and would start chine walking around 49-50 mph. With 23 srx over hub exhaust would do 52 with no chine walking. RPMs right around 5300-5400. Both cruised 37.5 mph at 4000 rpms.

After jack old 22 raker 54.5mph and did not chine walk till maxed out. 23 srx 56 mph and did not walk till maxed out and trimmed up. RPMs with both props 5700. The cruise speed remained basically the same but engine is now with neutral trim while cruising for cruising speeds. I decided to try a newer shiny 24 raker to bring the rpms into the recommenced range. The 24 ran 55 mph at 5400 rpms trimmed way up. Lots of slip here? I believe due to the fact as I trim up the bow flies but the stern gets pushed down creating drag. The engine needs to be higher for all out speeds? I have not altered the lower unit and am not planning too at this point. This is my fast Whaler not a speed boat and I use it for everything from running in the open ocean to shooting the flats. With the 24 raker the cruising speed went up to 40 mph at 4000rpms which is real nice and fast. The normal range of RPMs I run are 3000-4000 this range picked up the most because I can now run a larger pitch prop. This range averaged about a 3mph increase for each given RPM with the 24.

I thought I once ran the boat 57mph with a 24 raker and lite load (basically nothing in the boat) directly on the transom 3 or 4 years ago, but I must have been dreaming, using some strange speed telling device or the engine is starting to show its age.

posted 03-28-2008 11:02 PM ET (US)            

A good way to tell if you can raise your engine anymore is to install a water pressure gauge. Simply raise your engine until it can't maintain 12-15 psi. At speeds lower than 75-80 mph lower unit modifications (nose cones) aren't typically necessary or beneficial. There is usually plenty of water fed to the lower unit at elevated engine heights at these speeds.

Thanks again for the info.

posted 04-02-2008 12:50 PM ET (US)            

Runpasthefence, I was thinking about a water pressure gage. Right now the tell tail is strong. I don't think I’m going to raise the engine more. It seems to be at a good height for all around use. Your definitely right about a nose cone. There is no real need with my application. The thought of plugging the top water intake holes did cross my mind. I was thinking of putting some screws in there or something, but now I don't think I will.

Sal, I understand what you are saying and your probably right. It just seems like I have a lot of spray coming from the outside stern edges of the hull at high speeds trimmed out.

I'm surprised that people with 90hp Mercs can reach 55 mph. I guess that is because they have a different gear ratio and possibly and narrower more water dynamic gear case? More set up time?

posted 04-06-2008 05:08 PM ET (US)            

How does your boat come out of the hole with the 23 SRX? Does she pop right out, or is it sluggish?

posted 04-06-2008 07:36 PM ET (US)            

The 23 srx is better then the 22 raker in all aspects except one. You cannot go slow. If you try to just stay on plan at around 20 mph she will cavitate real bad. Then you have to fall off plan completely and then throttle back up. If you just give it throttle as she cavitates, she just cavitates more. This is because the exhaust goes over the prop making it worse.