Hull vs. Max HP

[SD Browning]

I know this has been discussed here before but I couldn’t find any threads on it when I did a search…..Question is, what is the risk of overpowering manufactures specified HP for a boat hull? Weight, boat control, safety, insurance, etc….

Specifics: I have a (2000) 1800 Lund Fisherman that is currently rigged with a 125 Mercury 2over2 and a 9.9 Merc tiller kicker, I can currently run in the upper 30’s (with average amount of gear) and cruise best around the 36 mph range.…..I know max HP rating for this boat is 175HP, but it seems like finding a 175 (used anyway) is not an easy task. I am not sure how much performance I would gain out of upgrading to say a 135 or 150 Optimax or if I am unable to find a 175 and would bump up to a 200 HP? Just looking at options and opinions, I am not a speed demon but at the same time I do a lot of fishing on the Missouri River and it would be nice to have the extra power on those rough days and longer runs on the days the wind does lay down.

Thanks guys (& gals)! I have learned a ton from this website!!

[REW]

SD,
You can put what ever engine your want on what ever boat that you want.

Let your insurance company know what boat you have and what motor you have. If the insurance company insures the boat with that motor you are good to go. If it doesn't - look for a different insurance company or use a different motor.

I have never heard of any one ever getting a ticket for a motor that is larger than the motor plate on the boat, but that is again up to local enforcement.

If you do go larger with the motor - one of the biggest concerns is that the boat is structurally sound enough to take the weight and power of the different motor.

If you can engineer the change, are willing to live with any potential outcome - it is certainly your choice.

It is a free country.

Be safe
REW

[ShimanoElite]

This was discussed with the sponsored insurance agent here on WC. To make a long story short, don't overpower your rig. The risk far outweighs the reward. You probably wont even find a dealer who will overpower your rig in the first place so its a moot point.

[BW]

A 150hp motor will probably be easier to find and shares the same block with the 175. A 150 will probably give you quite a bit of performance gain going to a V6 block over the motor you have now. As said, I wouldn't overpower it. The difference between a 150 and 175 in most brands is only a couple of mph.

[4JawChuck]

My Lund 1700 is rated for 115hp, the newer hulls of this size are rated for 125's.

Mine is rigged with a 200HP 1991 Merc currently...wish I had saved a few more beans for a 225 Promax. The weight difference between the engines is minimal, the performance is the where I like it...weight in the boat hardly makes a difference in speed. Cruise rpm is around 3800 rpm with a 25" four blade at 40 mph...it's perfect and at that rpm its quiet and just purring.

Most Lunds have 2" thick transom of this size, the same as performance bass boats with large V6 engine ratings...there is no flex at speed on my boat. This is important, a transom only 1.5" thick isn't enough for a large engine...most boats rated around 90HP usually are like this.

Do your homework, the hull has to be structurally sound to begin with...most floors are plywood and only screwed down. My hull has aluminum diamond plate structurally riveted down with polyurethane sealant to bond it into one large large rigid box.

Know what your doing before you overpower, a survey by a qualified marine surveyor would be an excellent investment...they have experience in high power craft and proper knowledge of hull inspection.

SD Browning,
I have a 2000 model 1800 Lund Fisherman with a 135 Optimax. 4 kids, wife, gear, 3/4 fuel, will normally run around 40 or maybe slightly more on a calm glass day. This is with a 3 blade 19" pitch aluminum prop at wot about 5200 rpm- 5500 is max rpm for my motor. With say 1/4 tank fuel, just me in the boat, and flat calm will run upper 40's. I tried a Mercury Enertia 19"SS prop last weekend- made a lot of difference. On plane faster, way more bow lift and held the water way better in the corner- max speed with my wife and I & 3/4 full of fuel on somewhat choppy water was 46 at 5300 rpm. I think you would definitely gain something by stepping up to a 135/150. It is the exact same engine, but a difference in how it is tuned from what I understand. Will you gain enough to justify the cost? I guess that's up to you.
Dan Tonak

[zummy]

http://www.walleyecentral.com/forums...d.php?t=160958

[hempbake1]

Used to have the same boat, Had a 150 yamaha vmax ox66 2 stroke on it. With a 21 pitch pro series yammy prop i could run 48-50 with 2 people and gear and full fuel all day long. That combo worked fantastic.