Surfing behind direct drive engine set-up

[jcb512]

Hello all,
Sorry if I am asking a repeated question. My boys have been hot on surfing and I am not in the market for a new boat right now so I got some ballasts for my 2006 Direct Drive Outback (310 Carb Indmar). My bags take us to the weight limit and I am very careful to stay below it, but wondering if there is any concern about the engine or anything I need to be cautious of for it? We are loading the surf side with a 500 and the back under the seat with another 500 will the listing cause a problem with enough oil in the pan to protect the engine correctly? I have watched the press and it seems normal at 60-65 when I am at surfing speed of 9 mph.

Thanks so much for any advice and stay safe all.

[996scott]

I don't think there is a problem as long as your engine oil is full. Add a suck gate to the opposite side and you should be good to go. You may need a different prop if the boat is struggling to get up to speed.

[jcb512]

Thanks so much 996Scott, for your response and advice. I will look for a gate or make one.

Take care.

[yearround]

Hello all,
... My bags take us to the weight limit ...

Thanks so much for any advice and stay safe all.

you might be about the only one who seems to mind the weight limit. but like scott said, load up the boat and add a suck gate and you will have a great time. I have a gate that i made a couple years ago that we don't use anymore. I can send it to you if you want. PM you number or email and i can send you a pic etc.

[Isaguel]

Being u have a shallow hull, and you need to displace a good amount of water to get a surfable wave, you will not be able to list the boat that much, safely, as you will have little freeboard. I think u should rely more on the wake gate and less on listing and put as much weight in as u can in. I'd add 3-400 lbs up front so you an increase total displacement without sinking your back end, and weigh the back with the 500lb evenly on each side and then use passengers weight sitting on surf side to create some list, and then mostly depend on the wake gate to create the surf side wave predominance. Build a larger WG that'll push more water.

[Tommy2slow]

I used to surf with our MC Prostar 197. I put a 400# bag on the bow seat on the surf side, a 750# bag on the floor in front of the rear bench slid over as far as possible to the surf side and another 750# bag beside the engine surf side. Had to be super careful to not dip the bow when retrieving a downed surfer but it works. I never tried a suck gate but I suspect that would help you a lot. You will have to be careful that you don’t get water in any vents when listed over like that, I had to put masking tape over a couple of mine. Make sure that you are equipped with the correct prop.

[jcb512]

Hello all, happy summer.
Coming back to a question I had last year on surfing behind my 2006 Outback with 310 carb Indmar with the a 3 blade prop. At the end of last summer we blew a head gasket on the engine. This is the second time in 7 years we blew a head gasket last time was due to a ton of weeds and inexperienced driver. This time we didn't have any thing similar to that all season. Only thing I can think of was the amount of surfing we were doing with 1000 ballasts and wake gate. I talked to the dealer about it and they said what I am doing shouldn't be a problem. So this year surfing I have been closely watching the temp gauge and noticed it climbs up right to 180 (stays on left side of numbers) when we are going along at 9-10mph then immediately drops down when we stop. As a reference when I ski at 30mph my temp sits around 160-165. The engine also sounds a bit more "growly" when surfing. My questions are, should I be worried about the temp rising? Any suggestions on fixing or managing the temp? Is the growly sound because I am overworking bearings or bad bearings on the shaft? As always I really appreciate the help from this group. Take care.

[HFarr]

I don't think 180 degree temp is any problem for the engine, but as far as the drive trane handling the extra loads, I couldn't say for sure. Just keep a close check on anything that feels sloppy or may have extra play.

Sent from my moto z4 using Tapatalk

[HFarr]

Check your raw water impeller for any chips or missing blades/fins or wear. It doesn't take too much to make a difference with them. Putting a load on the engine for surfing is going to naturally make it run a little harder, thus a little hotter exhaust on the manifolds. Would be like towing extra heavy loads with your truck. They tend to run a bit hotter when working harder. 180 is not dangerous for that motor.

Sent from my moto z4 using Tapatalk

[Tommy2slow]

What rpm are you surfing at? DD props are usually pretty big sobI would be worried about low rpm. If you turning less than 2500 rpm surfing that is an enormous amount of stress on your engine. Might be the reason for the high temps and head gasket issue.

[noahcentineo3]

I don't think the engine will be affected by the 180-degree temperature, but I can't tell for sure if the drive train will be able to handle the additional stresses. Simply keep an eye on anything that feels sloppy or appears to have excess play.
2 player games (https://2player.co)
Tapatalk was used to send this message from my Moto Z4.

[zabooda]

Tommy was right on. Look at your torque curves for your setup versus a surf boat and modify accordingly to optimize your power plant. I know a 1:1 tranny won't hack it. Your boat is doing something that it wasn't designed to do.

[jcb512]

Thanks everyone for the responses, as always great support from this group.

Tommy2slow and zabooda, I am curious more about your feedback. I am not sure the RPM's I will have to look at that next week but you are saying that I want them to be above 2500 to be easier on the engine? Would changing to a 4 blade prop put me in a better spot to reduce the stress on the engine? In regards to the torque curves, I don't know how to find that. I did some google searching but didn't find an easy answer, there was a lot about electric motors but I didn't see much about gas boat ones. If the tranny is 1:1 do people with DD's change that out to surf with them or is this something I just shouldn't do if I don't want to be replacing a head gasket again? Thanks so much again for all the great help I appreciate all of it. Have a good weekend everyone!

[Tommy2slow]

I can’t help you with finding the torque curve for your engine but being normally aspirated you can comfortably ball park guess that it doesn’t really wake up until somewhere above 2000rpm. Lots of people surf with DD with no issues so it can be done. You will just need to prop the boat to get the rpm a little higher. My MC is a DD and I tried surfing with it. Surf speed RPM was around 1700 rpm and the engine didn’t like that at all. I don’t know what pitch that prop is but my MC has a top speed of 44mph so it is probably pretty big. I’m thinking 17-19 pitch. Most of the surf boats on this forum have a prop in the 13-16 range plus a reduction transmission. Top speeds in the neighborhood hood of 32-38 mph and and the engine rpm when surfing of 3500-4200 rpm. I swapped my 16 pitch prop on my Mojo for a 13 and it works really well. My top speed dropped to 32mph but I live on a small lake so it’s all good. You will have to compromise as your boat will not be comfortable both pulling a surfer and pulling a barefoot skier (no boat can do that) so you will have to do some soul searching lol.

[Tommy2slow]

Sorry, I did a bit of research and the prop on my MC actually has a pretty small pitch prop in the 13-15 range probably. The 1:1 works to achieve the higher top speed but works against you when trying to surf with the boat. Having said that, your easiest and most economic option is a re-prop. Talk to Ken at ACME and he can help you with some great options.

[zabooda]

Here are the torque curves. It looks like 2500-3000 rpm is max torque. Get with a smart prop specialist and give the salesman the low down on your boat and what you want to do.

https://www.gearvendors.com/cghptorque.html