'83 Lund "Sirius" total gut and rebuild

[nurseman]

So, I have got a theoretical question for everyone, concerning HP ratings and overpowering. My hull is rated for a 90, BUT, the original transom was only 1" or 1[SUP]1[/SUP]/[SUB]4[/SUB]" (I'm not sure because it was mulch). When I rebuilt it, I made it 1[SUP]1[/SUP]/[SUB]2[/SUB]. So I am wondering if the original HP rating is still the max, or if there is room to boost it up. Now I'm not saying that I am planning on going with something bigger than a 90, I am simply curious what the more knowledgeable folks say/think about it. Obviously I would not go absolutely stupid and put something like a 150 on her, but if I were to come across a 100 or 115 for a reasonable price, would I be into the reckless category? or just good ole hot rodding?

I really think that a 90 will make that old girl fly, but I just wanted to get some outside opinions (just for the fun of it)

 

[zool]

Transom thickness doesn't really equate to hp capacity, tho it does allow it to hold more weight, like in a 4 stroke situation.

Its usually calculated with hull length, and transom width.

For example 16' (l) x 5.5' (tw) x 2 = 176 -90 = 86 or a 90hp

that's per Title 33-Code of Federal Regulations-Subpart 183.53

your boat looks great btw

 

[Mark72233]

Nurseman just my opinion but if my boat was built as well as your boat I would have no concerns with going with a little more HP like you said 100-115 not a 150hp. It may not pass a Coast Guard inspection but I think it would hold that size motor with no problem.

 

[Woodonglass]

This is a guide for HP Ratings for insurance...


- This is to only be used as a guide.
- You can round your final HP number to the closest multiple of 5. (31 HP would round to 30 HP. 33 HP would round to 35 HP)


Step One - Compute your Factor

A. Length of Boat x Transom Width (measure in feet: 14, 15.5,16, etc).



Step Two - Compare your factor to H.P. rating

A. 0-35 = 3 hp
B. 36-39 = 5 hp
C. 40-42 = 7.5 hp
D. 43-45 = 10 hp
E. 46-52 = 15 hp



Step Three - If your factor is over 52 (Choose only A or B)

A. With Remote Steering (steering wheel) and at least 20" transom height

Maximum HP = (Your factor x 2) - 90

Example: 19' 6" long , 7 feet wide = (19.5 x 7 x 2) - 90 = 183 (Round up in multiples of 5. This boat's max is 185 hp).


B. With Tiller Steering (hand or extension) or less than 20" transom height (Choose only 1 or 2)

1. Flat bottom, or hard chined boats (hull has hard angles)

Max HP = (Your factor x 0.5) - 15

2. Soft chine, rounded hulls

Max HP = (Your factor x 0.8) - 25

It should be noted that most insurance companies won't pay if they consider your boat to be overpowered, EVEN if your NOT AT FAULT!!!! In some states, the Lake Patrol can pull your registration if the feel you're overpowered.

In your case, a 110 or 115 prolly wouldn't raise suspicion. But I'm no expert either!!!:noidea:

 

[52FordF2]

Even though it didn't happen, wonder how many clamps "theoretically" would Nurseman use to flip his boat? :lol:

 

[Corjen1]

Nurseman, here are my thoughts....

Sometime in the 70's they changed horse power rating from "at the crank" to "at the prop"... point is, my boat for example...is a 68, rated for a 110 motor. By today's standards, the equivalent would be 100 hp (guessing a 10% loss through the drive train) If I put a modern 110 motor, (rated at the prop) I would be applying 20 HP more than originally intended.

The other thing to think about is at what RPM does your motor make its projected max HP rating? 4800, 5000, 5500??? Would have to look at your HP vs torque curve charts. Point is, in normal use, general day to day forces applied to your structure are you applying the max??? Not likely, how often do you run MAX/wide open throttle? When you are there, how long do yo dwell at that rating? If you typically are below that rating then what does the # on the side of your motor matter.

On an insurance perspective, if you were to, god forbid, have an accident, you likely would not get anything and be liable by the fact you deliberately exceeded the limit of your vessel. You may even get ticketed by your local fish cops depending on your state laws.

For all boats, they are designed to meet the regulations of the time of manufacture with a safety margin. During my build, I have by far exceeded the original design, in material types/design form and application.

For me and my boat, I installed a modern 115 HP, actual applied 20-25 hp over what it was rated for in 1968. I have every bit of confidence that the hull and structure will support the added HP. I also have every bit of confidence I will get it snapped off on me if I were to ever have a accident involving another vessel or person and it came to litigation.

You boat, your build...you decision. Hope Ive helped some in making it.

 

[nurseman]

Thanks for all the comments guys! I appreciate everyone's thoughts. When the time comes to put some power on her, I will most likely stay within the mfg HP rating. As a boating newbie, I just wanted to get some experienced opinions on the subject.
I have decided to not use the old 50 horse merc that came on the boat. I got it running (sort of), and the compression numbers did come up from where they were, but the spread between the cylinders got really big. The compression was 80, 90, 85, and 85 in cyl 1,2,3,4 respectively. I did what was suggested and put some oil in the spark plug holes, bought a new tester, and managed to get it running for 10ish minutes. I rechecked the compression and got 105, 135, 130, and 120 in cyl 1,2,3,4. Now I realize that I could probably run it for awhile, or even have it rebuilt, but the truth of the matter is that I'm not a mechanic, and I HATE working on stuff. So instead of spending money on a 50 year old motor, I'm gonna spend it on something newer that will reliably run. Might try to part out the old merc on evil-bay or something...

Gonna focus on getting the interior and trailer done for now. Will try and post some pictures soon.

 

[Teamster]

A modern 90 horse ought to push it very well,.................

 

[nurseman]

A modern 90 horse ought to push it very well,.................

Kinda what I was thinking.

 

[Woodonglass]

I had a 62' 40 hp on the BF. She was rated for a 70hp. I looked very hard for a 70hp but couldn't find one. I was not happy with the performance soooo Corjen1 made me a heck of deal on his 76' 85hp Rude' and I jumped on it. Now the BF performs like I want. I truly believe a more modern 90 hp will be the right way to go.

 

[nurseman]

I don't know where the summer went, but I have finally gotten around to doing some actual boat work again! BUT, I haven't been totally slacking, I have done some boat "related" things this summer. For quite awhile, my work schedule was pretty crazy, and my days off were erratically spaced, making it hard to get motivated to go out and work on the boat. So I took my daughter fishing (a lot) on my days off, which is always a good use of time in my opinion! I even have some pics!
Here's a couple of lunkers!






These are better! This one was 2.2 lb.



and this one was 8.4 lb. which is not bad for my neck of the woods. I had to hold on to her for that one, cause it was starting to pull her into the river!



We had catfish for lunch that day!

 

[nurseman]

My major project this summer was to convert my shop from LP to natural gas. My BIL has a heating and air company, and he helped my with the actual converting of the furnace. This will allow me to avoid the inevitable price hike in Jan/Feb when my tank always runs dry...So anyway, I finally got that done this last weekend, and my work schedule has lightened up just a bit, so I thought I would get back to the boat.

Got rid of the bow seating, gonna put a casting deck in.





Also got rid of the monster sized splash well, gonna do a deck in the back as well.



Still pondering the layout...

 

[zool]

Priceless....a summer well spent imo....

Didn't you catch anything except a buzz?

 

[nurseman]

So I was going to refurbish the trailer that came with the boat. However, after much thought, I decided that a different trailer was in order. I wanted to have a trailer that is wider, and with a heavier axle as well. So I did a bunch of looking around in my area, but the used selection of boat trailers was not stellar. So I have decided to just build my own trailer. I would rather spend the money on building something from scratch and know that it is the way I want it.

So my rebuild thread is going to have the obligatory trailer section in it as well. I started with a simple jig to keep the cross members the same.





and the finished members, with welds dressed up.



Here is the axle and spring assembly



More to come tomorrow (hopefully!)

 

[Tnstratofam]

Nice summer progress. Fishing with the family counts as boat work in my book. Looks like you're doing a great job teaching your little ones what fishing is all about.

So along with your impressive painting skills you're adding trailer fabrication as well. You must be a gluten for punishment.

Seriously though looking forward to more progress.:thumb:

 

[Woodonglass]

Hmmm, I didn't see any Clamps being used in the welding process!!! I thought you ALWAYS had to use CLAMPS!!!!! FISHING IS BOAT WORK!!!
I LOVE your BOAT MATES!!!!

Nice to have you back on the forum. Look forward to watching the Trailer progress!!!eace:

 

[sphelps]

Hmmm, I didn't see any Clamps being used in the welding process!!!:

Hold on Woody if you look in the second pic you will see a clamp on the edge of the work table .. I'm sure the Mayor of Clampville used it somehow in the fabrication ..
Great that you took the time to get the little anglers out for some fishing fun ! Makes the catfish taste way better knowing who landed em !

 

[Woodonglass]

Dang!!! Sure enuf, I missed that C-Clamp!!!! I stand Cow-Rected!!!!!

 

[nurseman]

Got a bunch more done on the trailer. Got pics too, but you have to wait till tomorrow to see them. I don't have time tonight to go through the whole posting process.

 

[Mikeopsycho]

Pretty cool NM! Can't find exactly what you're looking for.......just build one yourself. :thumb: I like your attitude. Just curious, what are you welding with? Stick, wire-feed ? Keep up the good work!

Great way to pass the time, fishin' with the youngon's! :fish2: