raising 15hp outboard on transom using wood spacer? (with pics)

[kg25]

Thanks for the interior picture. From that view the boat looks pretty much like a standard 14' Lund, with some additions to the interior. It does not look to have too much excess weight. A healthy 15 HP motor should get it moving fairly well.

If it were me, I would have the existing prop rebuilt (run your spare for now) and see if that improves things. Also take a look at the bottom of the boat, and using a straightedge look for damage in the last 6' or so of hull. If there are bends or damage, that can cause all sorts of issues with planing.

I'll look closely for any damage, but I haven't noticed any in the past.

[kg25]

Hey 20, have no fear, just drive it like you stole it, smile and wave!

KG- Here is a pic of a boat I had a long time ago that had similar planing issues due to the short 8' length and no way to redistribute weight, except for my butt. I ran a 20 HP motor, spinning a 9 1/2 X 13 two blade prop and it did about 35 MPH. The only way to get it to plane off was to climb out over the front and hang on until the bow leveled and it took off (sound familiar?). Worked the same way with a passenger (note the OH S*** handle behind the seat). Once it planed it was a blast to drive. I just had to get the set-up right. We even pulled skiers behind it, just had to pick them up from another boat with a rope hand off!

Yikes! That looks like it would be quite the ride and fun to drive.

[polarsusd81]

I have a suspicion that you are not getting everything out of the motor. Your prop pitch is probably off. I have a 14' Lund with a 15 Mariner on it. When I got it it had a 9" dia (?) x 12" pitch prop on it. I could barely get on plane by myself, and with more than me, not a chance. I went down to a 9"(?) x 9 1/4" pitch prop and it pops up on plane like nobodies business. Turning a taller pitch prop, your motor doesn't have enough power to push the added weight in the boat so it never gets up to optimal running RPMs. Go down in pitch, the motor turns the prop easier and it will allow you to get to optimal running RPMs. Old prop, bare boat I was at 32 mph on a GPS. Boat mods, fully flat floor, casting deck, storage compartment, anchors, 8-12 rod combos, two group 27 batts, 6 gallons of gas and two guys I still get 18 mph out of it. Same boat by the way.

Pretty sure that tag on the back of your boat is not original, cause the most they ever rated on those 14' lunds was 35 and about 585 lbs of gear or people. Yours is near double that for capacity. Not too hard to drill out rivits and grab a different tag, not smart either.

Questionmark on the diameter cause I can't remember if that is the correct diameter right now or not.

[kg25]

Look what I just found doing a google search (A pdf brochure of all 1968 Lund boats):

http://www.lundboats.com/pdfs/old-catalogs/1968-alum.pdf

Page 8 has all the specs for 1968 boats! My capacity plate matches exactly to the S-14 Big Fisherman.

The actual pdf might be a bit easier to read, but I copied a couple sections of the brochure.

Centerline = 14'

Beam = 65"

Transom Width = 58"

Depth Amidship = 24"

Depth at Bow = 30"

Hull Thickness = .064"

Approximate Weight = 215lbs

OBC-HP rating, Outboard = 50

Load Capacity, Outboard = 1195lbs

Seats = 4

[kg25]

I have a suspicion that you are not getting everything out of the motor. Your prop pitch is probably off. I have a 14' Lund with a 15 Mariner on it. When I got it it had a 9" dia (?) x 12" pitch prop on it. I could barely get on plane by myself, and with more than me, not a chance. I went down to a 9"(?) x 9 1/4" pitch prop and it pops up on plane like nobodies business. Turning a taller pitch prop, your motor doesn't have enough power to push the added weight in the boat so it never gets up to optimal running RPMs. Go down in pitch, the motor turns the prop easier and it will allow you to get to optimal running RPMs. Old prop, bare boat I was at 32 mph on a GPS. Boat mods, fully flat floor, casting deck, storage compartment, anchors, 8-12 rod combos, two group 27 batts, 6 gallons of gas and two guys I still get 18 mph out of it. Same boat by the way.

Pretty sure that tag on the back of your boat is not original, cause the most they ever rated on those 14' lunds was 35 and about 585 lbs of gear or people. Yours is near double that for capacity. Not too hard to drill out rivits and grab a different tag, not smart either.

Questionmark on the diameter cause I can't remember if that is the correct diameter right now or not.

Thanks for the reply! So once I get my tach, I should check to see if it is running in the optimum RPM range at WOT with my current prop. If it is not, I may benefit from a lower pitch prop which would increase the RPM's at WOT, thus increasing my speed? Or, there may possibly be something else wrong with my motor that is not allowing it to get to appropriate RPM's?

I have a tiny tach ordered, so once I get that, I can do some further testing with RPM's.

[polarsusd81]

Cool find on the Lund catalog. I stand corrected. 50 on one of the old S14s would be insane. Mine is a 72, exact same size specs, but horsepower and load capacity are lower. I thought I saw you tried a new prop, did you match the size of the one you have? Check the prop dims, stamped on a blade or the hub, and report back. Anything over 10" pitch and it'll never plane properly with it built like that.

Having a lower pitched prop will require less power to turn, so you can make it into midrange rpms, get on plane, and then gain a little speed top end as the motor is pushing less of the boat through the water. Less drag gives your motor the ability to reach optimal running rpms.

[kg25]

Cool find on the Lund catalog. I stand corrected. 50 on one of the old S14s would be insane. Mine is a 72, exact same size specs, but horsepower and load capacity are lower. I thought I saw you tried a new prop, did you match the size of the one you have? Check the prop dims, stamped on a blade or the hub, and report back. Anything over 10" pitch and it'll never plane properly with it built like that.

Having a lower pitched prop will require less power to turn, so you can make it into midrange rpms, get on plane, and then gain a little speed top end as the motor is pushing less of the boat through the water. Less drag gives your motor the ability to reach optimal running rpms.

Yeah, I took the prop off my 9.9 and it was the exact same 9.5 diameter and 10 pitch, which is what the service manual said came with the motor The service manual says alternative props are 10 diameter and 5 pitch or 9.25 diameter and 8 pitch. I ordered a 9.25x8 today to have to try as well. I can experiment with that new prop and see how it makes the boat perform.

I need to get the tach to do more testing though.

[fishadb]

I have a 73 Lund 14 deep v with a plywood floor above the benches and an 82 30hp mariner and get just about 30mph out of it, it is rated at 35 horses. My buddy has a 70 shallow v with a 25 hp evinrude and goes in the low twenties.

[kg25]

I got the Tiny Tach and installed it last night. I wasn't able to get to a lake, but I ran it on muffs just to check to make sure the Tiny Tach was setup correctly. I think I got it installed right. I had it in neutral and on the lowest idle on the throttle and it was hovering around 600 rpms. Does that seem about right? Next step is to get on the lake and do some more testing.

[polarsusd81]

So did you ever get this thing figured out? Was it the prop? Were you making it into the optimal RPM range with the old one? Did raising the motor do anything for you? What's the verdict?

One way to help others learn is by posting the results you found, it will help us all diagnose problems easier in the long run.