Pro-Line 251 I/O to Suzuki outboard conversion

a7ewizard

I've posted enough I should edit this section
Jun 4, 2009
108
120
SAN RAFAEL,CA USA
Name
WARREN WEISENBURG
Boat
251,PRO-LINE, WIZARD
I took my '98 PL 251 and converted it from an I/O to a bracketed OB. There was some project creep and some other modifications along the way. I am very happy with the end result
.

A bit of history...... I took delivery in January 1998. I ordered it with a 7.4 Gi Volvo Penta duo-prop. Engine and outdrive were replaced with a 5.7 Gxi in 2003. About 2007, I had an aftermarket hardtop installed. The boat has over 3800 hours of running time.

Last year, I began the renovation. I decided to do this because this boat fits my needs almost perfectly! Easy to take it out alone but fishes 3-4 guys well. Economical, great range, fish boxes, great storage, trailerable, overnighter package with stove and macerated head.

Over the years and with the availability of more powerful and reliable outboards, this make over was more and more on my wish list. I only had a very basic working experience with fiberglass. I decided to take this on......I did ALL the work myself with the exception of removing the old block and hanging the new Suzuki.
DSCN0334.JPG

I found a buyer for my VP power package! He took a test drive and gave me a deposit. The removal began.

DSCN0061.JPG

2017-02-14 16.24.51.jpg



The bilge was a mess! I used degreasers, Simple Green, and lots of elbow grease. Then came the sanding and grinding dressed in full Tyvex suit, gloves, goggles and respirator. To say this work was absolutely awful is an understatement!

The aft end of these stringers were hollow to allow for through bolting the motor brackets. I also discovered that the hollow stringers were full of water! I believe water had simply leaked in from the top cut-outs at the top of each stringer past screwed on and un-sealed covers. Once dried out, I poured in 4# expanding foam, glassed the stringers, reinforced the stringer/transom/ hull joints, and gel coated the bilge areas I could reach.

The transom cut for the outdrive showed no signs of delamination or moisture intrusion. Of course, with Divinycell core, it can't rot either.
This no-wood construction was a main reason I bought a Pro-Line in the first place.

I thought long and hard about closing up the transom hole. I knew my bracket would span this area and not put direct contact on it. The cut was pretty irregular and I didn't think enlarging it to mate to a more regular shaped plug was a good idea; removing more transom could weaken it. So, I poured in expanding foam, sandwiched by 2 pieces of parchment paper lined plywood. Worked perfectly! Fiberglassed over it both inside and out.
DSCN0114.JPG

DSCN0122.JPG

DSCN0129.JPG

DSCN0131.JPG

DSCN0143.JPG

DSCN0150.JPG


Turned my attention to the transom. It was warped and curved in a couple of ways. The top of the cutout (at the top of the outdrive) had a bit of a nose to it; like the weight of the drive had pulled the transom out and aft a bit. The back edge, from port to starboard was concaved in about 1/2 inch overall.

I had been working with Stainless Marine on building a single engine bracket for me. I wanted it full width so this curvature in the transom was a problem. I also wanted more flotation than their standard bracket because I planned to add a larger bait tank (more on this later).

It took a lot of sanding to get the transom flat. Then I added layers of glass, core-cell, and thickened resin to build out the transom where the bracket would be bolted.

DSCN0157.JPG

DSCN0177.JPG

DSCN0184.JPG


I made a template for drilling the 20 bolt holes. My friend and I did a dry fit. The next day and 2 tubes of 5200 later, the bracket was in place!

DSCN0185.JPG

20170507_163452.jpg


One of the other improvements was to the helm. I removed it to do some filling and repairs. Re-painted the top of the helm areas. Cleaned 19 years of crud from the sliding cabin door since the tracks were finally accessable.

I found some switch panels on Ebay. Re-used and added to the original Carling switches and bought new rocker covers for them. I flush mounted all new Raymarine electronics. Always wanted an autopilot, but the I/O installation was too expensive. I have one now.


Some before and after photos:
DSCN0021.JPG

DSCN0237.JPG

DSCN0254.JPG

DSCN0255.JPG

DSCN0330.JPG


Another desire was for a larger installed bait tank. I searched online for one that would fit inside the transom area. Couldn't find one....decided to try and build my own. A ton of work but it works great! Again, never done anything like this before.

I designed the tank to be contained within the transom cap. I cut out the transom sink and re-used the existing lid and moulded lip for the new bait tank. The tank I bonded to the underside of the cap using high strength polyurethane construction adhesive. After a few days set, I stood on one exposed edge of the tank. It is not about to come detached. It is between 20 and 25 gallons filled.

I added a Coosa/fiberglass cap where the old bait tank had been. This surface later covered with a Starboard cutting station.
DSCN0093.JPG

DSCN0265.JPG

DSCN0271.JPG

DSCN0273.JPG

DSCN0276.JPG

DSCN0279.JPG

DSCN0279.JPG

DSCN0302.JPG

DSCN0308.JPG

DSCN0337.JPG


The new bait tank meant I needed to relocate the 2 batteries. I built a Coosa/fiberglass battery tray to span the stringers. I changed the electrical system to a dual circuit design; an engine and a house/electrics. I bought a battery switch cover and installed it at the transom tuna door. No more reaching in to switch on the battery from my knees (as you get older, most of you can appreciate this!).

I added a Blue Seas fuse panel to eliminate most individual fuse holders. This also added more ground points. I eliminated all remote switches so all pumps and lights are helm controlled.

Lots of additional tasks: Suzuki harness to the helm. Pull steering hoses. Wire runs for hull LED, auto-pilot pump, and wash down pump. Re-purposed I/O blower circuit for bait tank LED. Rigged new DF300AP. Added new connectors to all existing circuits and spliced and cut as required. Relocated battery charger, bilge and wash down pumps. Ran new fuel line and installed new filter assembly.

DSCN0326.JPG

DSCN0307.JPG


With the engine mounted and the electrical system sorted, I had to do more fiberglass repairs. Removing the I/O blower system left 2 cutouts on either side of the hull. These were pretty easy to glass and fill and gelcoat. I ordered from Spectrum (iboats.com) since they have a matched gel coat color for my '98 Pro-Line. I have to say it was a pretty good match for a 20 year old boat. I can see it because I know where to look.....

Using 20# Coosa, I glued in some pieces to form the aft corner of the engine cut out. I glassed and filled and rolled on a few layers of gelcoat using a fine foam roller (learning some tricks along the way). This resulted in a pretty good finish! Not mold-like but pretty smooth anyway. Didn't I say this is a 20 year old boat.

DSCN0340.JPG
DSCN0345.JPG


I made a hatch cover and rolled on some Kiwi Grip to match my existing sole of the cockpit. I enlarged the vertical cut out slightly for better access. I had a custom cover made from boatoutfitters.com. They also did the cleaning station for me.

This last picture shows the finished cockpit and transom. It is so roomy and more fishable. No more jumping over the doghouse of the I/O. Easier to open the fish boxes. Remove the hatch cover and I have excellent access to the batteries, pumps, filter, and components.

DSCN0360.JPG

DSCN0361.JPG

20171120_161148.jpg

OK, so many of you must be wondering about handling and performance.

I swapped a 320 hp VP for 300 hp Suzuki. Once upon a time, this hull was available as either an I/O or a bracketed OB. Stainless Marine was the OEM supplier at that time. During my conversations and due diligence, I was very reassured that this hull was a great candidate for this conversion....

The Suzuki is much more quiet across the entire RPM range. I traded away about 400 pounds but the engine sits farther aft. The boat's stern floats about 2 inches higher than before. In the first photo of this thread, you can see the old scum line for comparison. When drift fishing, I don't get water sloshing in under the transom door like I did before; maybe it is because the stern is a bit higher or maybe it's due to the full width bracket. The bow rise coming onto plane is very slight. With full tabs and trim, I can plane at about 15 knots.

The two best propellers I have tried thus far are the Suzuki 3 blade in 18.5 pitch and a Powertech OFX 4 blade in 19 pitch. I am getting anywhere from 2.2 to 2.6 mpg at 30 mph depending on fuel load with a full curtain package using the PT prop.
 
Last edited:

GOFAST88

WORKHARD-FISHHARD
Sep 8, 2012
416
398
Murrieta
Name
Tyler
Boat
18' Bayrunner
Very cool! I would love to build A skipjack pilot house and do the same thing. Any pics of how you patched the out drive unit? What Bracket manufacture?
 
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bman440440

I am the one who knocks!!!
Sep 8, 2010
2,722
1,148
San Diego 92117
Name
B-MAN
Boat
Heisenberg(20' Maxum), Sip N' Slide (33' 2 deck w/slide) Ships & Giggles (32' double deck pontoon)
I took my '98 PL 251 and converted it from an I/O to a bracketed OB. There was some project creep and some other modifications along the way. I am very happy with the end result
.

A bit of history...... I took delivery in January 1998. I ordered it with a 7.4 Gi Volvo Penta duo-prop. Engine and outdrive were replaced with a 5.7 Gxi in 2003. About 2007, I had an aftermarket hardtop installed. The boat has over 3800 hours of running time.

Last year, I began the renovation. I decided to do this because this boat fits my needs almost perfectly! Easy to take it out alone but fishes 3-4 guys well. Economical, great range, fish boxes, great storage, trailerable, overnighter package with stove and macerated head.

Over the years and with the availability of more powerful and reliable outboards, this make over was more and more on my wish list. I only had a very basic working experience with fiberglass. I decided to take this on......I did ALL the work myself with the exception of removing the old block and hanging the new Suzuki.
View attachment 966162
I found a buyer for my VP power package! He took a test drive and gave me a deposit. The removal began.

View attachment 966163
View attachment 966164


The bilge was a mess! I used degreasers, Simple Green, and lots of elbow grease. Then came the sanding and grinding dressed in full Tyvex suit, gloves, goggles and respirator. To say this work was absolutely awful is an understatement!

The aft end of these stringers were hollow to allow for through bolting the motor brackets. I also discovered that the hollow stringers were full of water! I believe water had simply leaked in from the top cut-outs at the top of each stringer past screwed on and un-sealed covers. Once dried out, I poured in 4# expanding foam, glassed the stringers, reinforced the stringer/transom/ hull joints, and gel coated the bilge areas I could reach.

The transom cut for the outdrive showed no signs of delamination or moisture intrusion. Of course, with Divinycell core, it can't rot either.
This no-wood construction was a main reason I bought a Pro-Line in the first place.

I thought long and hard about closing up the transom hole. I knew my bracket would span this area and not put direct contact on it. The cut was pretty irregular and I didn't think enlarging it to mate to a more regular shaped plug was a good idea; removing more transom could weaken it. So, I poured in expanding foam, sandwiched by 2 pieces of parchment paper lined plywood. Worked perfectly! Fiberglassed over it both inside and out.View attachment 966167
View attachment 966168
View attachment 966169
View attachment 966170
View attachment 966171
View attachment 966172

Turned my attention to the transom. It was warped and curved in a couple of ways. The top of the cutout (at the top of the outdrive) had a bit of a nose to it; like the weight of the drive had pulled the transom out and aft a bit. The back edge, from port to starboard was concaved in about 1/2 inch overall.

I had been working with Stainless Marine on building a single engine bracket for me. I wanted it full width so this curvature in the transom was a problem. I also wanted more flotation than their standard bracket because I planned to add a larger bait tank (more on this later).

It took a lot of sanding to get the transom flat. Then I added layers of glass, core-cell, and thickened resin to build out the transom where the bracket would be bolted.

View attachment 966173
View attachment 966174
View attachment 966175

I made a template for drilling the 20 bolt holes. My friend and I did a dry fit. The next day and 2 tubes of 5200 later, the bracket was in place!

View attachment 966177
View attachment 966178

One of the other improvements was to the helm. I removed it to do some filling and repairs. Re-painted the top of the helm areas. Cleaned 19 years of crud from the sliding cabin door since the tracks were finally accessable.

I found some switch panels on Ebay. Re-used and added to the original Carling switches and bought new rocker covers for them. I flush mounted all new Raymarine electronics. Always wanted an autopilot, but the I/O installation was too expensive. I have one now.


Some before and after photos:
View attachment 966179
View attachment 966180
View attachment 966181
View attachment 966182
View attachment 966183

Another desire was for a larger installed bait tank. I searched online for one that would fit inside the transom area. Couldn't find one....decided to try and build my own. A ton of work but it works great! Again, never done anything like this before.

I designed the tank to be contained within the transom cap. I cut out the transom sink and re-used the existing lid and moulded lip for the new bait tank. The tank I bonded to the underside of the cap using high strength polyurethane construction adhesive. After a few days set, I stood on one exposed edge of the tank. It is not about to come detached. It is between 20 and 25 gallons filled.

I added a Coosa/fiberglass cap where the old bait tank had been. This surface later covered with a Starboard cutting station.
View attachment 966186
View attachment 966187
View attachment 966190
View attachment 966191
View attachment 966192
View attachment 966193
View attachment 966193
View attachment 966194
View attachment 966195
View attachment 966197

The new bait tank meant I needed to relocate the 2 batteries. I built a Coosa/fiberglass battery tray to span the stringers. I changed the electrical system to a dual circuit design; an engine and a house/electrics. I bought a battery switch cover and installed it at the transom tuna door. No more reaching in to switch on the battery from my knees (as you get older, most of you can appreciate this!).

I added a Blue Seas fuse panel to eliminate most individual fuse holders. This also added more ground points. I eliminated all remote switches so all pumps and lights are helm controlled.

Lots of additional tasks: Suzuki harness to the helm. Pull steering hoses. Wire runs for hull LED, auto-pilot pump, and wash down pump. Re-purposed I/O blower circuit for bait tank LED. Rigged new DF300AP. Added new connectors to all existing circuits and spliced and cut as required. Relocated battery charger, bilge and wash down pumps. Ran new fuel line and installed new filter assembly.

View attachment 966199
View attachment 966200

With the engine mounted and the electrical system sorted, I had to do more fiberglass repairs. Removing the I/O blower system left 2 cutouts on either side of the hull. These were pretty easy to glass and fill and gelcoat. I ordered from Spectrum (iboats.com) since they have a matched gel coat color for my '98 Pro-Line. I have to say it was a pretty good match for a 20 year old boat. I can see it because I know where to look.....

Using 20# Coosa, I glued in some pieces to form the aft corner of the engine cut out. I glassed and filled and rolled on a few layers of gelcoat using a fine foam roller (learning some tricks along the way). This resulted in a pretty good finish! Not mold-like but pretty smooth anyway. Didn't I say this is a 20 year old boat.

View attachment 966201 View attachment 966205

I made a hatch cover and rolled on some Kiwi Grip to match my existing sole of the cockpit. I enlarged the vertical cut out slightly for better access. I had a custom cover made from boatoutfitters.com. They also did the cleaning station for me.

This last picture shows the finished cockpit and transom. It is so roomy and more fishable. No more jumping over the doghouse of the I/O. Easier to open the fish boxes. Remove the hatch cover and I have excellent access to the batteries, pumps, filter, and components.

View attachment 966208
View attachment 966209
View attachment 966210
OK, so many of you must be wondering about handling and performance.

I swapped a 320 hp VP for 300 hp Suzuki. Once upon a time, this hull was available as either an I/O or a bracketed OB. Stainless Marine was the OEM supplier at that time. During my conversations and due diligence, I was very reassured that this hull was a great candidate for this conversion....

The Suzuki is much more quiet across the entire RPM range. I traded away about 400 pounds but the engine sits farther aft. The boat's stern floats about 2 inches higher than before. In the first photo of this thread, you can see the old scum line for comparison. When drift fishing, I don't get water sloshing in under the transom door like I did before; maybe it is because the stern is a bit higher or maybe it's due to the full width bracket. The bow rise coming onto plane is very slight. With full tabs and trim, I can plane at about 15 knots.

The two best propellers I have tried thus far are the Suzuki 3 blade in 18.5 pitch and a Powertech OFX 4 blade in 19 pitch. I am getting anywhere from 2.2 to 2.6 mpg at 30 mph depending on fuel load with a full curtain package using the PT prop.
I'm just curious about one thing... why did you repower from a 7.4 to a 5.7 in 2003? And BTW that is bad ass... and mad skills sir!
 
Last edited:

a7ewizard

I've posted enough I should edit this section
Jun 4, 2009
108
120
SAN RAFAEL,CA USA
Name
WARREN WEISENBURG
Boat
251,PRO-LINE, WIZARD
The 7.4 broke down; came to a sudden stop after a loud bang. I never tore into it to find the cause.
Repowered with the 5.7. Size and weight wise it was a better fit for the boat. Better on gas too.
 
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skipjackrobert

I've posted enough I should edit this section
Apr 2, 2013
7,522
2,593
The OC
Name
Rob
Boat
The Constitution or Tomahawk with Stan
Very cool!
 

hbouldin1216

I've posted enough I should edit this section
May 10, 2012
1,351
1,056
Lodi, CA
Name
Henry Bouldin
Boat
14 Gregor - Tinacious
coulda fooled me with those glass skills. Really impressed with the new Suzukis. Bad ass rig that will surely continue to rack up the hours.
 

ltran0614

I've posted enough I should edit this section
May 8, 2013
628
373
Orange
Name
L Train
Boat
27' Farallon Whaleback & 27' Radon LRB
Wow talk about mad skillz!!! :D
 

CENCOASTFISH

I've posted enough I should edit this section
Jan 26, 2009
331
27
SANTA MARIA/CA/USA
Name
B. A. STEWART
Boat
PRO-LINE 231 WA B2
Great post A7 , I wish owner of old Pro-line owners board would have answered when i wanted to take it over from them. dont know if they met misfortune or some other cause.
you were always a good contributor there.
I'm watching your thread for application to my 231 but not sure when the time comes it will be worth the trouble.
I will straight edge my transom some time and see whats up there.
low plane speed is excellent for choppy water north of pt conception where weather limits speed .
how does it do with the bait tank filled? sounds like no problems.
hope she gives you many more years of good fishing.
thanks for effort documenting, cant believe your a newby to some of that laminating and finishing.
good work
 

rustman

I've posted enough I should edit this section
Aug 4, 2005
578
789
Irvine, Ca
Name
Rusty
Boat
1986 Cabo 216 Cuddy-Con
Very nice job on the entire project. You have a new boat now without paying the $100k it would cost to replace it.
 

baaadlybent

I've posted enough I should edit this section
Sep 5, 2006
1,170
459
Fullerton/Bahia de los Angeles
Name
Doug
Boat
26' Striper "Baaadly Bent", 21' Bayrunner Baja "Vamonos", 15' Gregor "Little Vamonos"
Hi. I'm installing a new fly-by-wire 300AP. Did you power the NMEA2000 from a keyed power source or straight to the batteries or switch? I'm using C10 color gauges and not sure which way to go. If a keyed power source then you lose them (and anything else powered by NMEA2000) when you shut down the outboard. Not sure I want to leave the key in the "on" position to see gauges. Thanks.
 
Last edited:

a7ewizard

I've posted enough I should edit this section
Jun 4, 2009
108
120
SAN RAFAEL,CA USA
Name
WARREN WEISENBURG
Boat
251,PRO-LINE, WIZARD
Hi. I'm installing a new fly-by-wire 300AP. Did you power the NMEA2000 from a keyed power source or straight to the batteries or switch? I'm using C10 color gauges and not sure which way to go. If a keyed power source then you lose them (and anything else powered by NMEA200) when you shut down the outboard. Not sure I want to leave the key in the "on" position to see gauges. Thanks.
I wired my Raymarine electonics backbone into the Suzuki NMEA 2000 network.
With the key in the on position, the network stays energized even when the engine is not running.
A word of caution. Suzuki network is based on Simrad type connectors. Raymarine requires splicing backbone cables.
 

a7ewizard

I've posted enough I should edit this section
Jun 4, 2009
108
120
SAN RAFAEL,CA USA
Name
WARREN WEISENBURG
Boat
251,PRO-LINE, WIZARD
How is the ride between the I/o and the OB?
I don't think the ride is any different. The OB is lighter. Similar to the difference between full fuel and less fuel. A heavy boat rides smoother.

The OB requires more trimming is the main handling difference.
 

baaadlybent

I've posted enough I should edit this section
Sep 5, 2006
1,170
459
Fullerton/Bahia de los Angeles
Name
Doug
Boat
26' Striper "Baaadly Bent", 21' Bayrunner Baja "Vamonos", 15' Gregor "Little Vamonos"
I wired my Raymarine electonics backbone into the Suzuki NMEA 2000 network.
With the key in the on position, the network stays energized even when the engine is not running.
A word of caution. Suzuki network is based on Simrad type connectors. Raymarine requires splicing backbone cables.
Thanks for the response. When you leave the key on does the hour meter of the C10 gauges start counting, or only when the outboard is actually running?
 

a7ewizard

I've posted enough I should edit this section
Jun 4, 2009
108
120
SAN RAFAEL,CA USA
Name
WARREN WEISENBURG
Boat
251,PRO-LINE, WIZARD
Thanks for the response. When you leave the key on does the hour meter of the C10 gauges start counting, or only when the outboard is actually running?
Hour meter counts only when the engine is running.
I thought about powering the NMEA 2000 network from 2 sources and adding a power isolator ( network can only have a single power source to any component) but realized I only needed the network to work with the engine on anyway. Simple system without multiple helms or mfds.
 

baaadlybent

I've posted enough I should edit this section
Sep 5, 2006
1,170
459
Fullerton/Bahia de los Angeles
Name
Doug
Boat
26' Striper "Baaadly Bent", 21' Bayrunner Baja "Vamonos", 15' Gregor "Little Vamonos"
After thinking about this I guess the outboard computer actually keeps track of the hours running since the C10 is only a display. Not like an old school hobbes meter. Great install.
 

yakmandan

I've posted enough I should edit this section
May 30, 2007
650
779
AZ.
Name
DAN
Boat
19ft Bayrunner Baja
Wow!! Great job and great report. I'd bet you're one of those guys that can take on almost any project and make it look like a pro did it.
 

a7ewizard

I've posted enough I should edit this section
Jun 4, 2009
108
120
SAN RAFAEL,CA USA
Name
WARREN WEISENBURG
Boat
251,PRO-LINE, WIZARD
:-)
Wow!! Great job and great report. I'd bet you're one of those guys that can take on almost any project and make it look like a pro did it.
Thanks for the complements. I'm no pro.
Look closely and there are some 8/10 spots. Takes alot more time and effort for a back yard guy to reach professional results.
Just completed a 300 hr service on the Suzuki. I'm still extremely happy with the entire refit; engine, raymarine electronics + autopilot, bait tank, etc.
 
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kaosx10

Master of KAOS
Mar 15, 2013
266
155
pinon hills, ca
Name
jeff
Boat
25' Farallon - Grizzly Bear
Awesome job! and wow this looks too similar to my farallon build. Wish I had seen this before I started.
 

Reel 007

I've posted enough I should edit this section
Jun 12, 2006
1,499
623
Glendora Ca
Name
Leon
Boat
28 Wellcraft Coastal "vagabond'
Fantastic work, I have a small suggestion, replace the horn switch cover with a red/orange one also you can get switch covers with the names engraved in.
 

a7ewizard

I've posted enough I should edit this section
Jun 4, 2009
108
120
SAN RAFAEL,CA USA
Name
WARREN WEISENBURG
Boat
251,PRO-LINE, WIZARD
Fantastic work, I have a small suggestion, replace the horn switch cover with a red/orange one also you can get switch covers with the names engraved in.
Yeah, my buddy doesn't like my labels either.