Removing Foam

[YeOldeRusty]

I've been running a 2017 Xpress 16DBX that I bought about 10 months ago. I've spent plenty of time getting it setup to run how I like it. When I bought it the motor was mounted directly to the transom and was running 31 mph with a 12p ss prop with a Yamaha 50 4 stroke. With 7" of setback with a jackplate and kick plate as well as playing around with props, I have it running a hair shy of 40mph.

In my never-ending quest for more performance, I've decided to try to reduce the weight of the boat. I believe Xpress boats are notorious for having waterlogged foam, so I'd like to look at removing the foam and replacing with oil jugs or something similar. I'm curious if anyone has any advice for pulling up the floor/rear deck in a way that makes it easy to reinstall. If I wanted to test and see if the foam was waterlogged, could I drill a hole in the floor and test the foam that comes out?

 

[airshot]

No mention of max rpm at wot....that means everything !!
The rest means nothing, motor must be proped to run at max Rpm as recomended by mfgr !! Above or below is harming your engine...

 

[LDUBS]

Any mention of fine tuning props catches my attention because I think I might benefit from moving up a pitch or two. You gained quite a bit of speed, which is awesome. Out of put curiosity, you went from a 12p to a what pitch?

I don't know your boat so can't help with pulling up the floor. If you can pull up a section, I would do that before drilling a hole.

 

[YeOldeRusty]

No mention of max rpm at wot....that means everything !!
The rest means nothing, motor must be proped to run at max Rpm as recomended by mfgr !! Above or below is harming your engine...

Motor is propped appropriately and I switch depending on situation. With the 14p YBS clone I run now it sits at 5900 rpm with me and fishing gear. I've squeezed enough juice out of it with setup that my options for more performance are more HP or less weight.

 

[YeOldeRusty]

Any mention of fine tuning props catches my attention because I think I might benefit from moving up a pitch or two. You gained quite a bit of speed, which is awesome. Out of put curiosity, you went from a 12p to a what pitch?

I don't know your boat so can't help with pulling up the floor. If you can pull up a section, I would do that before drilling a hole.

Gotta have a tach before you really start playing the prop game. Otherwise you're just shooting in the dark. The original prop was a 12p Powertech Reb3. After raising the motor up about 3 inches with 7" of setback, I was running ~35mph on the rev limiter. I repropped to a 14p YBS clone and that got me to the 38-39 I'm running now at ~6000rpm.

My boat is heavy enough that when I try to over-trim, the bow starts hopping. I really like running a prop like the YBS because it's a semi-cleaver with low rake so it's much more of a stern-lifting prop. This allows me to trim out more and run the motor higher on the jack plate.

During duck season I have been running a 4 blade 12p Powertech SCB4. It's a similar design to the YBS but with 4 blades and slightly more cup. I haven't been able to do any real speed testing with it because I'm always carrying a lot of gear/people during duck season. It jumps out of the hole and I can almost run the jack plate all the way up with that prop.

 

[LDUBS]

Gotta have a tach before you really start playing the prop game. Otherwise you're just shooting in the dark. The original prop was a 12p Powertech Reb3. After raising the motor up about 3 inches with 7" of setback, I was running ~35mph on the rev limiter. I repropped to a 14p YBS clone and that got me to the 38-39 I'm running now at ~6000rpm.

My boat is heavy enough that when I try to over-trim, the bow starts hopping. I really like running a prop like the YBS because it's a semi-cleaver with low rake so it's much more of a stern-lifting prop. This allows me to trim out more and run the motor higher on the jack plate.

During duck season I have been running a 4 blade 12p Powertech SCB4. It's a similar design to the YBS but with 4 blades and slightly more cup. I haven't been able to do any real speed testing with it because I'm always carrying a lot of gear/people during duck season. It jumps out of the hole and I can almost run the jack plate all the way up with that prop.

Thanks. My Honda is rated at 50HP at 5,750 rpm. Has PT&T, so trimming it out is pretty easy. I'm currently running an 11.125 x 13p going 32 mph at 6,200 rpm WOT. Been toying with going to an 11 x 15p. The $250 price tag for OEM (Solas/Honda) has been enough to keep me from experimenting too much.

 

[YeOldeRusty]

Thanks. My Honda is rated at 50HP at 5,750 rpm. Has PT&T, so trimming it out is pretty easy. I'm currently running an 11.125 x 13p going 32 mph at 6,200 rpm WOT. Been toying with going to an 11 x 15p. The $250 price tag for OEM (Solas/Honda) has been enough to keep me from experimenting too much.

Have you played around with jack plates and setback? Raising motor up is a great way to gain rpms. Less motor in the water means less drag slowing you down. Just raising mine up a few inches gained me a few mph. Depending on design, some props you can run in ventilating conditions where they're out of the water slightly.

 

[LDUBS]

Have you played around with jack plates and setback? Raising motor up is a great way to gain rpms. Less motor in the water means less drag slowing you down. Just raising mine up a few inches gained me a few mph. Depending on design, some props you can run in ventilating conditions where they're out of the water slightly.

No, haven't tried a jack plate. Not something I really want to do on this boat. My real issue is to reduce the WOT rpm's to spec's. And, by doing so gain a few mph.

 

[thill]

40 MPH with a 50 HP outboard is an excellent conversion rate. Xpress makes some fast hulls.

Before you go digging in the foam, why not do a core test. Take a piece of 1/2" copper pipe, or something similar, and push it down through the foam and see if it's wet.

People had me convinced that my boat had wet foam, and they were planning out for me how I was going to replace it. I did a core check through the drain hole area, and it was bone dry. They seemed disappointed, but I was thrilled, and saved myself a lot of work.

Make sure it's broke before you fix it.

 

[flatheadsteve]

Xpress uses an injected expanding foam that will not absorb water. Removing it would be a major ordeal it's literally in every cavity and void. 40mph is moving with a 50hp on that hull it was designed for shallow running in the timber they make a pad hull if speed is what your after.

 

[YeOldeRusty]

Xpress uses an injected expanding foam that will not absorb water. Removing it would be a major ordeal it's literally in every cavity and void. 40mph is moving with a 50hp on that hull it was designed for shallow running in the timber they make a pad hull if speed is what your after.

I've always heard the pad hull rides great, but you need a good bit more than 50hp to really ride on the pad. Makes sense because Xpress boats are pretty heavy when compared to other duck boats (Edge, Havoc, etc.)

As far as running shallow in the timber, I've noticed whenever I'm behind Edge or other duck boat that they ride completely on top of the water. Like they draft less than an inch on plane. I would guess my boat sits at least 6 inches in the water when I'm on plane. Would like to get the hull to ride a little higher for shallow running.

 

[FuzzyGrub]

As far as running shallow in the timber, I've noticed whenever I'm behind Edge or other duck boat that they ride completely on top of the water. Like they draft less than an inch on plane. I would guess my boat sits at least 6 inches in the water when I'm on plane. Would like to get the hull to ride a little higher for shallow running.

Six inches seems too deep to be running on plane at near 40mph. What is its static draft?

 

[YeOldeRusty]

Six inches seems too deep to be running on plane at near 40mph. What is its static draft?

Couldn't tell you exactly. I'd say I've got 5-6 inches of freeboard at the transom sitting still. Sits pretty low. Mostly because the 50hp weighs 250lbs and I've added 7 inches of setback. Sure that adds leverage to the rear.

If I trim down it rides a bit shallower. That kills my speed obviously because I'm burying the nose.

 

[Still Afloat]

Thanks. My Honda is rated at 50HP at 5,750 rpm. Has PT&T, so trimming it out is pretty easy. I'm currently running an 11.125 x 13p going 32 mph at 6,200 rpm WOT. Been toying with going to an 11 x 15p. The $250 price tag for OEM (Solas/Honda) has been enough to keep me from experimenting too much.

Interesting thread. Doing a quick search on semi cleaver props I found an online vendor Getaprop.com. I’ve never used this vendor but, I found the following statement interesting:

NOTE: If you are not satisfied with your purchase within the first 30 days, we will exchange your propeller for a different pitch for a nominal fee.

Obviously, swapping SS props isn’t cheap so this could be appealing depending on that nominal fee.

 

[Still Afloat]

Gotta have a tach before you really start playing the prop game. Otherwise you're just shooting in the dark. The original prop was a 12p Powertech Reb3. After raising the motor up about 3 inches with 7" of setback, I was running ~35mph on the rev limiter. I repropped to a 14p YBS clone and that got me to the 38-39 I'm running now at ~6000rpm.

My boat is heavy enough that when I try to over-trim, the bow starts hopping. I really like running a prop like the YBS because it's a semi-cleaver with low rake so it's much more of a stern-lifting prop. This allows me to trim out more and run the motor higher on the jack plate.

During duck season I have been running a 4 blade 12p Powertech SCB4. It's a similar design to the YBS but with 4 blades and slightly more cup. I haven't been able to do any real speed testing with it because I'm always carrying a lot of gear/people during duck season. It jumps out of the hole and I can almost run the jack plate all the way up with that prop.

Thanks for sharing. Are you doing anything special to assure the OB is getting an adequate amount of cooling water?

 

[YeOldeRusty]

Thanks for sharing. Are you doing anything special to assure the OB is getting an adequate amount of cooling water?

Just checking behind me occasionally to make sure it's pissing. I plan on adding a cavitation plate from Circle S machine which should help keep water pressure around the prop/water intake. Hopefully that will let me run motor higher and maybe make it plane out easier. They make inserts for your water intake that funnel water better. I can't remember the name of the company though.

Edit: company is TR machining on instagram/facebook. They're inserts that scoop water into the intake.

 

[flatheadsteve]

I've always heard the pad hull rides great, but you need a good bit more than 50hp to really ride on the pad. Makes sense because Xpress boats are pretty heavy when compared to other duck boats (Edge, Havoc, etc.)

As far as running shallow in the timber, I've noticed whenever I'm behind Edge or other duck boat that they ride completely on top of the water. Like they draft less than an inch on plane. I would guess my boat sits at least 6 inches in the water when I'm on plane. Would like to get the hull to ride a little higher for shallow running.

Your hull probably doesn't create as much lift as those other boats you see or they are running bigger outboards then what it's rated for and testing the limits. I see that a lot with duck boats. I would be pretty happy with the speed your getting I have a 20ft xpress with the hyperlift hull and a yamaha 150sho which supposedly is actually 175hp and I only hit mid 50s.

 

[flatheadsteve]

Just checking behind me occasionally to make sure it's pissing. I plan on adding a cavitation plate from Circle S machine which should help keep water pressure around the prop/water intake. Hopefully that will let me run motor higher and maybe make it plane out easier. They make inserts for your water intake that funnel water better. I can't remember the name of the company though.

Edit: company is TR machining on instagram/facebook. They're inserts that scoop water into the intake.

You may be going the wrong way on the jackplate. I have a hydraulic jackplate and have to drop it deeper as speed increases or it cavitatates.

 

[YeOldeRusty]

You may be going the wrong way on the jackplate. I have a hydraulic jackplate and have to drop it deeper as speed increases or it cavitatates.

In my experience with this boat it has been the opposite. The higher I can run the motor without cavitation, the faster it goes. Assuming I'm in open water and just going from A to B, I like to find that line where the prop is just about to blow out. That's where I get the most speed. As little drag in the water from lower unit as possible.

 

[YeOldeRusty]

Your hull probably doesn't create as much lift as those other boats you see or they are running bigger outboards then what it's rated for and testing the limits. I see that a lot with duck boats. I would be pretty happy with the speed your getting I have a 20ft xpress with the hyperlift hull and a yamaha 150sho which supposedly is actually 175hp and I only hit mid 50s.

I usually notice how high other boats ride when I'm running right there with them. So I don't think its a speed thing necessarily.

I am actually happy with the speed I'm getting with how it's set up now. I really think I've squeezed all the juice I can get without A. Losing weight (my original question), or B. Adding horsepower.

OutboardEFI recently came out with their tune for the Yamaha 50-70hp. Send out your ECU and they can get the 50 and 60 up into the high 70hp range. I haven't heard anyone complain about reliability issues after having their ECUs flashed. I'm out of warranty anyway.